CVE-2026-15176

A vulnerability exists in NGINX Plus and NGINX Open Source when a location is configured that uses the alias directive together with rewrite and a set or return directive referencing the $request_filename variable. Alternatively, the same result could be achieved when the $request_filename variable is used in an access log format directive. An unauthenticated attacker along with conditions beyond their control can exploit this vulnerability by sending crafted HTTP requests. This may cause a heap buffer overflow in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR. Impact: This vulnerability may allow remote attackers to cause a denial-of-service (DoS) on the NGINX system or to possibly trigger a code execution. There is no control plane exposure; this is a data plane issue only. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

NGINX is a free, open-source, high-performance HTTP server and reverse proxy, as well as an IMAP/POP3 proxy server.

Security Fix(es):

A vulnerability exists in NGINX Plus and NGINX Open Source when a location is configured that uses the alias directive together with rewrite and a set or return directive referencing the $request_filename variable. Alternatively, the same result could be achieved when the $request_filename variable is used in an access log format directive. An unauthenticated attacker along with conditions beyond their control can exploit this vulnerability by sending crafted HTTP requests. This may cause a heap buffer overflow in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR.

Impact: This vulnerability may allow remote attackers to cause a denial-of-service (DoS) on the NGINX system or to possibly trigger a code execution. There is no control plane exposure; this is a data plane issue only.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.(CVE-2026-15176)

A vulnerability exists in NGINX Plus and NGINX Open Source when a map directive uses regex matching and the root directive or access log format references the map's regex capture variables before referencing the map output variable. Alternatively, the same result could be achieved by using a non-cacheable variable in a string expression under certain conditions. An unauthenticated attacker along with conditions beyond their control can exploit this vulnerability by sending crafted HTTP requests. This may cause a heap buffer overflow in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR.

Impact:  This vulnerability may allow remote attackers to cause a denial-of-service (DoS) on the NGINX system or to possibly trigger a code execution. There is no control plane exposure; this is a data plane issue only.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.(CVE-2026-93479)

NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_core_module module. When asynchronous file I/O (AIO) is enabled in certain configurations, processing a Server Side Includes (SSI) page containing “include virtual” commands may trigger a Use-After-Free (UAF) in the NGINX worker process. This may cause memory corruption or a worker process crash. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR.

Impact: This vulnerability may allow remote attackers to cause a denial-of-service (DoS) on the NGINX system, corrupt its memory, or possibly trigger code execution. There is no control plane exposure; this is a data plane issue only.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.(CVE-2026-97205)

NGINX is a free, open-source, high-performance HTTP server and reverse proxy, as well as an IMAP/POP3 proxy server.

Security Fix(es):

A vulnerability exists in NGINX Plus and NGINX Open Source when a location is configured that uses the alias directive together with rewrite and a set or return directive referencing the $request_filename variable. Alternatively, the same result could be achieved when the $request_filename variable is used in an access log format directive. An unauthenticated attacker along with conditions beyond their control can exploit this vulnerability by sending crafted HTTP requests. This may cause a heap buffer overflow in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR.

Impact: This vulnerability may allow remote attackers to cause a denial-of-service (DoS) on the NGINX system or to possibly trigger a code execution. There is no control plane exposure; this is a data plane issue only.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.(CVE-2026-15176)

A vulnerability exists in NGINX Plus and NGINX Open Source when a map directive uses regex matching and the root directive or access log format references the map's regex capture variables before referencing the map output variable. Alternatively, the same result could be achieved by using a non-cacheable variable in a string expression under certain conditions. An unauthenticated attacker along with conditions beyond their control can exploit this vulnerability by sending crafted HTTP requests. This may cause a heap buffer overflow in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR.

Impact:  This vulnerability may allow remote attackers to cause a denial-of-service (DoS) on the NGINX system or to possibly trigger a code execution. There is no control plane exposure; this is a data plane issue only.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.(CVE-2026-93479)

NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_core_module module. When asynchronous file I/O (AIO) is enabled in certain configurations, processing a Server Side Includes (SSI) page containing “include virtual” commands may trigger a Use-After-Free (UAF) in the NGINX worker process. This may cause memory corruption or a worker process crash. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR.

Impact: This vulnerability may allow remote attackers to cause a denial-of-service (DoS) on the NGINX system, corrupt its memory, or possibly trigger code execution. There is no control plane exposure; this is a data plane issue only.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.(CVE-2026-97205)

Description When NGINX Plus or NGINX Open Source is configured with ssl_session_cache

shared:name:size

without an explicit ssl_session_ticket_key file directives to automatically rotate SSL session ticket keys, a remote unauthenticated attacker is able to forge client SSL sessions

in a non-deterministic manner that is beyond the attacker's control. An attacker could leverage this vulnerability to bypass verification of client certificates.

Impact

This vulnerability can lead to the exposure of resources or functionality to unintended actors, possibly providing attackers with access to sensitive information. There is no control plane exposure; this is a data plane issue only.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.(CVE-2026-97629)

NGINX is a free, open-source, high-performance HTTP server and reverse proxy, as well as an IMAP/POP3 proxy server.

Security Fix(es):

A vulnerability exists in NGINX Plus and NGINX Open Source when a location is configured that uses the alias directive together with rewrite and a set or return directive referencing the $request_filename variable. Alternatively, the same result could be achieved when the $request_filename variable is used in an access log format directive. An unauthenticated attacker along with conditions beyond their control can exploit this vulnerability by sending crafted HTTP requests. This may cause a heap buffer overflow in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR.

Impact: This vulnerability may allow remote attackers to cause a denial-of-service (DoS) on the NGINX system or to possibly trigger a code execution. There is no control plane exposure; this is a data plane issue only.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.(CVE-2026-15176)

A vulnerability exists in NGINX Plus and NGINX Open Source when a map directive uses regex matching and the root directive or access log format references the map's regex capture variables before referencing the map output variable. Alternatively, the same result could be achieved by using a non-cacheable variable in a string expression under certain conditions. An unauthenticated attacker along with conditions beyond their control can exploit this vulnerability by sending crafted HTTP requests. This may cause a heap buffer overflow in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR.

Impact:  This vulnerability may allow remote attackers to cause a denial-of-service (DoS) on the NGINX system or to possibly trigger a code execution. There is no control plane exposure; this is a data plane issue only.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.(CVE-2026-93479)

NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_core_module module. When asynchronous file I/O (AIO) is enabled in certain configurations, processing a Server Side Includes (SSI) page containing “include virtual” commands may trigger a Use-After-Free (UAF) in the NGINX worker process. This may cause memory corruption or a worker process crash. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR.

Impact: This vulnerability may allow remote attackers to cause a denial-of-service (DoS) on the NGINX system, corrupt its memory, or possibly trigger code execution. There is no control plane exposure; this is a data plane issue only.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.(CVE-2026-97205)

Description When NGINX Plus or NGINX Open Source is configured with ssl_session_cache

shared:name:size

without an explicit ssl_session_ticket_key file directives to automatically rotate SSL session ticket keys, a remote unauthenticated attacker is able to forge client SSL sessions

in a non-deterministic manner that is beyond the attacker's control. An attacker could leverage this vulnerability to bypass verification of client certificates.

Impact

This vulnerability can lead to the exposure of resources or functionality to unintended actors, possibly providing attackers with access to sensitive information. There is no control plane exposure; this is a data plane issue only.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.(CVE-2026-97629)

NGINX is a free, open-source, high-performance HTTP server and reverse proxy, as well as an IMAP/POP3 proxy server.

Security Fix(es):

A vulnerability exists in NGINX Plus and NGINX Open Source when a location is configured that uses the alias directive together with rewrite and a set or return directive referencing the $request_filename variable. Alternatively, the same result could be achieved when the $request_filename variable is used in an access log format directive. An unauthenticated attacker along with conditions beyond their control can exploit this vulnerability by sending crafted HTTP requests. This may cause a heap buffer overflow in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR.

Impact: This vulnerability may allow remote attackers to cause a denial-of-service (DoS) on the NGINX system or to possibly trigger a code execution. There is no control plane exposure; this is a data plane issue only.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.(CVE-2026-15176)

A vulnerability exists in NGINX Plus and NGINX Open Source when a map directive uses regex matching and the root directive or access log format references the map's regex capture variables before referencing the map output variable. Alternatively, the same result could be achieved by using a non-cacheable variable in a string expression under certain conditions. An unauthenticated attacker along with conditions beyond their control can exploit this vulnerability by sending crafted HTTP requests. This may cause a heap buffer overflow in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR.

Impact:  This vulnerability may allow remote attackers to cause a denial-of-service (DoS) on the NGINX system or to possibly trigger a code execution. There is no control plane exposure; this is a data plane issue only.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.(CVE-2026-93479)

NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_core_module module. When asynchronous file I/O (AIO) is enabled in certain configurations, processing a Server Side Includes (SSI) page containing “include virtual” commands may trigger a Use-After-Free (UAF) in the NGINX worker process. This may cause memory corruption or a worker process crash. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR.

Impact: This vulnerability may allow remote attackers to cause a denial-of-service (DoS) on the NGINX system, corrupt its memory, or possibly trigger code execution. There is no control plane exposure; this is a data plane issue only.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.(CVE-2026-97205)

Description When NGINX Plus or NGINX Open Source is configured with ssl_session_cache

shared:name:size

without an explicit ssl_session_ticket_key file directives to automatically rotate SSL session ticket keys, a remote unauthenticated attacker is able to forge client SSL sessions

in a non-deterministic manner that is beyond the attacker's control. An attacker could leverage this vulnerability to bypass verification of client certificates.

Impact

This vulnerability can lead to the exposure of resources or functionality to unintended actors, possibly providing attackers with access to sensitive information. There is no control plane exposure; this is a data plane issue only.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.(CVE-2026-97629)

A vulnerability exists in NGINX Plus and NGINX Open Source when a location is configured that uses the alias directive together with rewrite and a set or return directive referencing the $request_filename variable. Alternatively, the same result could be achieved when the $request_filename variable is used in an access log format directive. An unauthenticated attacker along with conditions beyond their control can exploit this vulnerability by sending crafted HTTP requests. This may cause a heap buffer overflow in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR. Impact: This vulnerability may allow remote attackers to cause a denial-of-service (DoS) on the NGINX system or to possibly trigger a code execution. There is no control plane exposure; this is a data plane issue only. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

A vulnerability exists in NGINX Plus and NGINX Open Source when a location is configured that uses the alias directive together with rewrite and a set or return directive referencing the $request_filename variable. Alternatively, the same result could be achieved when the $request_filename variable is used in an access log format directive. An unauthenticated attacker along with conditions beyond their control can exploit this vulnerability by sending crafted HTTP requests. This may cause a heap buffer overflow in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR.

Impact: This vulnerability may allow remote attackers to cause a denial-of-service (DoS) on the NGINX system or to possibly trigger a code execution. There is no control plane exposure; this is a data plane issue only.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

A vulnerability exists in NGINX Plus and NGINX Open Source when a location is configured that uses the alias directive together with rewrite and a set or return directive referencing the $request_filename variable. Alternatively, the same result could be achieved when the $request_filename variable is used in an access log format directive. An unauthenticated attacker along with conditions beyond their control can exploit this vulnerability by sending crafted HTTP requests. This may cause a heap buffer overflow in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR.

Impact: This vulnerability may allow remote attackers to cause a denial-of-service (DoS) on the NGINX system or to possibly trigger a code execution. There is no control plane exposure; this is a data plane issue only.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

A vulnerability exists in NGINX Plus and NGINX Open Source when a location is configured that uses the alias directive together with rewrite and a set or return directive referencing the $request_filename variable. Alternatively, the same result could be achieved when the $request_filename variable is used in an access log format directive. An unauthenticated attacker along with conditions beyond their control can exploit this vulnerability by sending crafted HTTP requests. This may cause a heap buffer overflow in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR.

Impact: This vulnerability may allow remote attackers to cause a denial-of-service (DoS) on the NGINX system or to possibly trigger a code execution. There is no control plane exposure; this is a data plane issue only.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

• CVE-2026-15176: fix heap buffer overflow in ngx_http_map_uri_to_path() when a location using "alias" maps a URI changed by "rewrite" before a new location is selected; reject the mapping while r->uri_changed is set

• CVE-2026-15176: reject "alias" URI to path mapping in ngx_http_map_uri_to_path() after a rewrite changed the URI and before a new location is selected, and invalidate the location after a standalone "break" following a rewrite, preventing a heap buffer overflow

• CVE-2026-15176: reject "alias" URI to path mapping in ngx_http_map_uri_to_path() after a rewrite changed the URI and before a new location is selected, and invalidate the location after a standalone "break" following a rewrite, preventing a heap buffer overflow

• CVE-2026-15176: reject "alias" URI to path mapping in ngx_http_map_uri_to_path() after a rewrite changed the URI and before a new location is selected, and invalidate the location after a standalone "break" following a rewrite, preventing a heap buffer overflow

• CVE-2026-15176: fix heap buffer overflow in ngx_http_map_uri_to_path() when a location using "alias" maps a URI changed by "rewrite" before a new location is selected; reject the mapping while r->uri_changed is set

• SECURITY UPDATE: heap buffer overflow via alias with rewrite and $request_filename
  • debian/patches/CVE-2026-15176-pre.patch: clear r->valid_location on a standalone "break" after the URI was rewritten
  • debian/patches/CVE-2026-15176.patch: reject URI to path mapping in ngx_http_map_uri_to_path() for an "alias" location once rewrite has changed the URI
  • CVE-2026-15176

• SECURITY UPDATE: heap buffer overflow when mapping a rewritten URI to a path in a location using alias
  • debian/patches/CVE-2026-15176.patch: reject URI to path mapping in ngx_http_map_uri_to_path() when r->uri_changed is set, so a rewrite that shortens the URI below the alias location prefix can no longer overflow the path buffer through $request_filename
  • CVE-2026-15176
• SECURITY UPDATE: use-after-free via duplicate subrequest finalization
  • debian/patches/CVE-2026-56434.patch: skip posting a request in ngx_http_post_request() if it is already posted, and reset the subrequest write event handler during finalization in ngx_http_finalize_request(), so an SSI subrequest double-posted during unbuffered proxying can no longer be finalized twice
  • CVE-2026-56434

• CVE-2026-15176: reject URI to path mapping in ngx_http_map_uri_to_path() while a rewrite has changed the URI and no new location has been chosen yet, closing a window that mapped requests in an aliased location to an incorrect path

• CVE-2026-15176: reject URI to path mapping in ngx_http_map_uri_to_path() while a rewrite has changed the URI and no new location has been chosen yet, closing a window that mapped requests in an aliased location to an incorrect path

• CVE-2026-15176: reject URI to path mapping in ngx_http_map_uri_to_path() while a rewrite has changed the URI and no new location has been chosen yet, closing a window that mapped requests in an aliased location to an incorrect path

• SECURITY UPDATE: heap buffer overflow in ngx_http_map_uri_to_path() when $request_filename is evaluated after a rewrite inside an "alias" location
  • debian/patches/CVE-2026-15176.patch: reject the URI to path mapping for an "alias" location while r->uri_changed is set, and clear r->valid_location in ngx_http_script_break_code() when the URI was changed, so a rewritten URI shorter than the location prefix is no longer mapped to a path
  • CVE-2026-15176

• SECURITY UPDATE: heap buffer overflow via post-rewrite URI to path mapping with alias
  • debian/patches/CVE-2026-15176.patch: in ngx_http_map_uri_to_path(), reject the mapping for a location using "alias" when r->uri_changed is set, so a rewritten URI shorter than the location prefix is no longer mapped to a path (e.g. via $request_filename)
  • debian/patches/CVE-2026-15176-2.patch: in ngx_http_script_break_code(), clear r->valid_location when the URI was changed, so the alias check also rejects the mapping after a standalone "break"
  • CVE-2026-15176

These are all security issues fixed in the nginx-1.31.7-1.1 package on the GA media of openSUSE Tumbleweed.

Root has patched CVE-2026-15176 in the nginx package for Root:Alpine:3.15. Multiple fixed versions available.

Root has patched CVE-2026-15176 in the nginx package for Root:Alpine:3.21. Multiple fixed versions available.

Root has patched CVE-2026-15176 in the nginx package for Root:Alpine:3.23. Multiple fixed versions available.

Root has patched CVE-2026-15176 in the nginx package for Root:Debian:12. Multiple fixed versions available.

Root has patched CVE-2026-15176 in the nginx package for Root:Debian:13. Multiple fixed versions available.

It was discovered that nginx incorrectly handled certain configurations using the alias directive together with rewrite rules. A remote attacker could possibly use this issue to cause nginx to crash, resulting in a denial of service, or execute arbitrary code. (CVE-2026-15176)

It was discovered that nginx incorrectly handled map directives using regex matching under certain circumstances. A remote attacker could possibly use this issue to cause nginx to crash, resulting in a denial of service, or execute arbitrary code. (CVE-2026-93479)

It was discovered that nginx incorrectly handled HTTP/3 requests when proxy_request_buffering was enabled. This issue only affected Ubuntu 26.04 LTS and Ubuntu 26.10. A remote attacker could possibly use this issue to inject data into proxied requests. (CVE-2026-95101)

It was discovered that nginx incorrectly handled asynchronous file I/O in certain configurations with Server Side Includes pages. A remote attacker could possibly use this issue to cause nginx to crash, resulting in a denial of service, or execute arbitrary code. (CVE-2026-97205)

It was discovered that nginx incorrectly handled SSL session ticket keys when configured with a shared session cache but without explicit ticket key rotation. This issue only affected Ubuntu 24.04 LTS, Ubuntu 26.04 LTS, and Ubuntu 26.10. A remote attacker could possibly use this issue to forge client SSL sessions and bypass client certificate verification. (CVE-2026-97629)

USN-8955-1 fixed vulnerabilities in nginx in Ubuntu 26.10, Ubuntu 26.04 LTS, Ubuntu 24.04 LTS, and Ubuntu 22.04 LTS. This update provides the corresponding update for Ubuntu 20.04 LTS, Ubuntu 18.04 LTS, Ubuntu 16.04 LTS, and Ubuntu 14.04 LTS.

In addition, this update fixes CVE-2026-42533 for these releases.

It was discovered that nginx incorrectly handled certain map directives using regex matching and capture variables. A remote attacker could possibly use this issue to crash nginx, resulting in a denial of service, or possibly execute arbitrary code. (CVE-2026-42533)

Original advisory details:

It was discovered that nginx incorrectly handled certain configurations using the alias directive together with rewrite rules. A remote attacker could possibly use this issue to cause nginx to crash, resulting in a denial of service, or execute arbitrary code. (CVE-2026-15176)

It was discovered that nginx incorrectly handled map directives using regex matching under certain circumstances. A remote attacker could possibly use this issue to cause nginx to crash, resulting in a denial of service, or execute arbitrary code. (CVE-2026-93479)

It was discovered that nginx incorrectly handled HTTP/3 requests when proxy_request_buffering was enabled. This issue only affected Ubuntu 26.04 LTS and Ubuntu 26.10. A remote attacker could possibly use this issue to inject data into proxied requests. (CVE-2026-95101)

It was discovered that nginx incorrectly handled asynchronous file I/O in certain configurations with Server Side Includes pages. A remote attacker could possibly use this issue to cause nginx to crash, resulting in a denial of service, or execute arbitrary code. (CVE-2026-97205)

It was discovered that nginx incorrectly handled SSL session ticket keys when configured with a shared session cache but without explicit ticket key rotation. This issue only affected Ubuntu 24.04 LTS, Ubuntu 26.04 LTS, and Ubuntu 26.10. A remote attacker could possibly use this issue to forge client SSL sessions and bypass client certificate verification. (CVE-2026-97629)