CVE-2026-8286

A vulnerability exists where a new transfer that uses STARTTLS to upgrade the connection might reuse an existing live connection even though the TLS configuration mismatches so it should not.

A vulnerability exists where a new transfer that uses STARTTLS to upgrade the connection might reuse an existing live connection even though the TLS configuration mismatches so it should not.

A vulnerability exists where a new transfer that uses STARTTLS to upgrade the connection might reuse an existing live connection even though the TLS configuration mismatches so it should not.

cURL is a computer software project providing a library (libcurl) and command-line tool (curl) for transferring data using various protocols.

Security Fix(es):

A vulnerability exists where a new transfer that uses STARTTLS to upgrade the connection might reuse an existing live connection even though the TLS configuration mismatches so it should not.(CVE-2026-8286)

A flaw in curl’s cookie parsing logic allows a malicious HTTP server to set 'super cookies' that bypass the Public Suffix List check. This enables an attacker-controlled origin to inject cookies that curl subsequently scopes and transmits to unrelated third-party domains.(CVE-2026-8924)

When reusing a libcurl handle for sequential transfers driven by environment-variable proxy configuration, libcurl fails to clear the proxy authentication state between requests. Specifically, if the initial transfer authenticates against proxyA using Digest auth, a subsequent transfer routed through proxyB erroneously leaks the Proxy-Authorization: header intended solely for proxyA.(CVE-2026-8927)

When a libcurl-based application performs transfers via SCP:// or SFTP:// and utilizes the CURLOPT_SSH_KEYFUNCTION callback, it may silently accept an untrusted server. This vulnerability occurs when a server presents a host key type that does not match the specific key type already recorded for that host in the known_hosts file. Instead of rejecting the mismatch, the callback mechanism fails to properly enforce the restriction, allowing the connection to succeed without warning and risking a potential man-in-the-middle attack.(CVE-2026-9547)

cURL is a computer software project providing a library (libcurl) and command-line tool (curl) for transferring data using various protocols.

Security Fix(es):

A vulnerability exists where a new transfer that uses STARTTLS to upgrade the connection might reuse an existing live connection even though the TLS configuration mismatches so it should not.(CVE-2026-8286)

A flaw in curl’s cookie parsing logic allows a malicious HTTP server to set 'super cookies' that bypass the Public Suffix List check. This enables an attacker-controlled origin to inject cookies that curl subsequently scopes and transmits to unrelated third-party domains.(CVE-2026-8924)

When reusing a libcurl handle for sequential transfers driven by environment-variable proxy configuration, libcurl fails to clear the proxy authentication state between requests. Specifically, if the initial transfer authenticates against proxyA using Digest auth, a subsequent transfer routed through proxyB erroneously leaks the Proxy-Authorization: header intended solely for proxyA.(CVE-2026-8927)

When a libcurl-based application performs transfers via SCP:// or SFTP:// and utilizes the CURLOPT_SSH_KEYFUNCTION callback, it may silently accept an untrusted server. This vulnerability occurs when a server presents a host key type that does not match the specific key type already recorded for that host in the known_hosts file. Instead of rejecting the mismatch, the callback mechanism fails to properly enforce the restriction, allowing the connection to succeed without warning and risking a potential man-in-the-middle attack.(CVE-2026-9547)

cURL is a computer software project providing a library (libcurl) and command-line tool (curl) for transferring data using various protocols.

Security Fix(es):

A use-after-free vulnerability exists in libcurl when an application configures an HTTP/2 stream-dependency tree via CURLOPT_STREAM_DEPENDS or CURLOPT_STREAM_DEPENDS_E, subsequently invokes curl_easy_reset(), and finally terminates the handle with curl_easy_cleanup(). During this final cleanup phase, libcurl attempts to access and modify an internal structure that was already freed during the reset operation.(CVE-2026-10536)

When a user invokes curl using a schemeless URL combined with --proto-default sftp (or scp), a disconnect occurs between the tool layer and libcurl. The tool layer incorrectly infers the URL scheme, which erroneously bypasses the initialization of critical SSH security options like CURLOPT_SSH_HOST_PUBLIC_KEY_SHA256 and CURLOPT_SSH_KNOWNHOSTS. Conversely, the libcurl runtime successfully honors CURLOPT_DEFAULT_PROTOCOL and establishes the connection via SFTP/SCP as specified. Because the tool layer skipped the security configuration, these SSH host verification options are silently omitted, causing curl to connect to an unverified SSH remote host without throwing an error.(CVE-2026-12064)

A vulnerability exists where a new transfer that uses STARTTLS to upgrade the connection might reuse an existing live connection even though the TLS configuration mismatches so it should not.(CVE-2026-8286)

A flaw in curl’s cookie parsing logic allows a malicious HTTP server to set 'super cookies' that bypass the Public Suffix List check. This enables an attacker-controlled origin to inject cookies that curl subsequently scopes and transmits to unrelated third-party domains.(CVE-2026-8924)

When reusing a libcurl handle for sequential transfers driven by environment-variable proxy configuration, libcurl fails to clear the proxy authentication state between requests. Specifically, if the initial transfer authenticates against proxyA using Digest auth, a subsequent transfer routed through proxyB erroneously leaks the Proxy-Authorization: header intended solely for proxyA.(CVE-2026-8927)

When a libcurl-based application performs transfers via SCP:// or SFTP:// and utilizes the CURLOPT_SSH_KEYFUNCTION callback, it may silently accept an untrusted server. This vulnerability occurs when a server presents a host key type that does not match the specific key type already recorded for that host in the known_hosts file. Instead of rejecting the mismatch, the callback mechanism fails to properly enforce the restriction, allowing the connection to succeed without warning and risking a potential man-in-the-middle attack.(CVE-2026-9547)

cURL is a computer software project providing a library (libcurl) and command-line tool (curl) for transferring data using various protocols.

Security Fix(es):

A use-after-free vulnerability exists in libcurl when an application configures an HTTP/2 stream-dependency tree via CURLOPT_STREAM_DEPENDS or CURLOPT_STREAM_DEPENDS_E, subsequently invokes curl_easy_reset(), and finally terminates the handle with curl_easy_cleanup(). During this final cleanup phase, libcurl attempts to access and modify an internal structure that was already freed during the reset operation.(CVE-2026-10536)

When a user invokes curl using a schemeless URL combined with --proto-default sftp (or scp), a disconnect occurs between the tool layer and libcurl. The tool layer incorrectly infers the URL scheme, which erroneously bypasses the initialization of critical SSH security options like CURLOPT_SSH_HOST_PUBLIC_KEY_SHA256 and CURLOPT_SSH_KNOWNHOSTS. Conversely, the libcurl runtime successfully honors CURLOPT_DEFAULT_PROTOCOL and establishes the connection via SFTP/SCP as specified. Because the tool layer skipped the security configuration, these SSH host verification options are silently omitted, causing curl to connect to an unverified SSH remote host without throwing an error.(CVE-2026-12064)

A vulnerability exists where a new transfer that uses STARTTLS to upgrade the connection might reuse an existing live connection even though the TLS configuration mismatches so it should not.(CVE-2026-8286)

A flaw in curl’s cookie parsing logic allows a malicious HTTP server to set 'super cookies' that bypass the Public Suffix List check. This enables an attacker-controlled origin to inject cookies that curl subsequently scopes and transmits to unrelated third-party domains.(CVE-2026-8924)

When reusing a libcurl handle for sequential transfers driven by environment-variable proxy configuration, libcurl fails to clear the proxy authentication state between requests. Specifically, if the initial transfer authenticates against proxyA using Digest auth, a subsequent transfer routed through proxyB erroneously leaks the Proxy-Authorization: header intended solely for proxyA.(CVE-2026-8927)

When a libcurl-based application performs transfers via SCP:// or SFTP:// and utilizes the CURLOPT_SSH_KEYFUNCTION callback, it may silently accept an untrusted server. This vulnerability occurs when a server presents a host key type that does not match the specific key type already recorded for that host in the known_hosts file. Instead of rejecting the mismatch, the callback mechanism fails to properly enforce the restriction, allowing the connection to succeed without warning and risking a potential man-in-the-middle attack.(CVE-2026-9547)

cURL is a computer software project providing a library (libcurl) and command-line tool (curl) for transferring data using various protocols.

Security Fix(es):

A use-after-free vulnerability exists in libcurl when an application configures an HTTP/2 stream-dependency tree via CURLOPT_STREAM_DEPENDS or CURLOPT_STREAM_DEPENDS_E, subsequently invokes curl_easy_reset(), and finally terminates the handle with curl_easy_cleanup(). During this final cleanup phase, libcurl attempts to access and modify an internal structure that was already freed during the reset operation.(CVE-2026-10536)

When a user invokes curl using a schemeless URL combined with --proto-default sftp (or scp), a disconnect occurs between the tool layer and libcurl. The tool layer incorrectly infers the URL scheme, which erroneously bypasses the initialization of critical SSH security options like CURLOPT_SSH_HOST_PUBLIC_KEY_SHA256 and CURLOPT_SSH_KNOWNHOSTS. Conversely, the libcurl runtime successfully honors CURLOPT_DEFAULT_PROTOCOL and establishes the connection via SFTP/SCP as specified. Because the tool layer skipped the security configuration, these SSH host verification options are silently omitted, causing curl to connect to an unverified SSH remote host without throwing an error.(CVE-2026-12064)

A vulnerability exists where a new transfer that uses STARTTLS to upgrade the connection might reuse an existing live connection even though the TLS configuration mismatches so it should not.(CVE-2026-8286)

A flaw in curl’s cookie parsing logic allows a malicious HTTP server to set 'super cookies' that bypass the Public Suffix List check. This enables an attacker-controlled origin to inject cookies that curl subsequently scopes and transmits to unrelated third-party domains.(CVE-2026-8924)

When reusing a libcurl handle for sequential transfers driven by environment-variable proxy configuration, libcurl fails to clear the proxy authentication state between requests. Specifically, if the initial transfer authenticates against proxyA using Digest auth, a subsequent transfer routed through proxyB erroneously leaks the Proxy-Authorization: header intended solely for proxyA.(CVE-2026-8927)

When a libcurl-based application performs transfers via SCP:// or SFTP:// and utilizes the CURLOPT_SSH_KEYFUNCTION callback, it may silently accept an untrusted server. This vulnerability occurs when a server presents a host key type that does not match the specific key type already recorded for that host in the known_hosts file. Instead of rejecting the mismatch, the callback mechanism fails to properly enforce the restriction, allowing the connection to succeed without warning and risking a potential man-in-the-middle attack.(CVE-2026-9547)

The curl packages provide the libcurl library and the curl utility for downloading files from servers using various protocols, including HTTP, FTP, and LDAP.

Security Fix(es):

• curl: curl: Authentication bypass due to incorrect connection reuse with Negotiate authentication (CVE-2026-1965)

• curl: curl: Information disclosure via OAuth2 bearer token leakage during HTTP(S) redirect (CVE-2026-3783)

• curl: curl: Man-in-the-middle attack via SSH host key bypass (CVE-2026-9547)

• curl: curl: Insecure connection establishment due to TLS configuration mismatch (CVE-2026-8286)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

The curl packages provide the libcurl library and the curl utility for downloading files from servers using various protocols, including HTTP, FTP, and LDAP.

Security Fix(es):

• curl: curl: Insecure connection establishment due to TLS configuration mismatch (CVE-2026-8286)

Bug Fix(es) and Enhancement(s):

• Regression of Rocky Linux-73788. The .9 revision appears to have broken the logic that forces NTLM to use HTTP/1.1. (JIRA:Rocky Linux-171912)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

A vulnerability exists where a new transfer that uses STARTTLS to upgrade the connection might reuse an existing live connection even though the TLS configuration mismatches so it should not.

The curl packages provide the libcurl library and the curl utility for downloading files from servers using various protocols, including HTTP, FTP, and LDAP.

Security Fix(es):

• curl: curl: Authentication bypass due to incorrect connection reuse with Negotiate authentication (CVE-2026-1965)
• curl: curl: Information disclosure via OAuth2 bearer token leakage during HTTP(S) redirect (CVE-2026-3783)
• curl: curl: Man-in-the-middle attack via SSH host key bypass (CVE-2026-9547)
• curl: curl: Insecure connection establishment due to TLS configuration mismatch (CVE-2026-8286)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

The curl packages provide the libcurl library and the curl utility for downloading files from servers using various protocols, including HTTP, FTP, and LDAP.

Security Fix(es):

• curl: curl: Insecure connection establishment due to TLS configuration mismatch (CVE-2026-8286)

Bug Fix(es) and Enhancement(s):

• Regression of AlmaLinux-73788. The .9 revision appears to have broken the logic that forces NTLM to use HTTP/1.1. (JIRA:AlmaLinux-171912)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

A vulnerability exists where a new transfer that uses STARTTLS to upgrade the connection might reuse an existing live connection even though the TLS configuration mismatches so it should not.

A vulnerability exists where a new transfer that uses STARTTLS to upgrade the connection might reuse an existing live connection even though the TLS configuration mismatches so it should not.

• SECURITY UPDATE: libcurl could reuse a connection for a STARTTLS transfer despite a mismatched TLS configuration.
  • debian/patches/CVE-2026-8286.patch: add an SSL-config match check before reusing a connection for a clear-text protocol that requests TLS, in lib/url.c.
  • CVE-2026-8286
• SECURITY UPDATE: a trailing-dot cookie domain could bypass the Public Suffix List check and set a super-cookie.
  • debian/patches/CVE-2026-8924.patch: trim trailing dots from the domains before the PSL check in lib/cookie.c.
  • CVE-2026-8924
• SECURITY UPDATE: libcurl could send proxy Digest credentials to the wrong proxy when the proxy is selected from environment variables on a reused handle.
  • debian/patches/CVE-2026-8927.patch: clear the proxy Digest state when the environment proxy changes, in lib/url.c and lib/urldata.h.
  • CVE-2026-8927

• CVE-2026-8286: require a matching SSL configuration before reusing a pooled connection for a clear-text transfer that upgrades via STARTTLS

• CVE-2026-8286: require a matching SSL configuration before reusing a pooled connection for a clear-text transfer that upgrades via STARTTLS

• CVE-2026-8286: url: fix connection reuse for starttls protocols

• CVE-2026-8286: url: fix connection reuse for starttls protocols

• CVE-2026-8286: require a matching SSL configuration before reusing a pooled connection for a clear-text transfer that upgrades via STARTTLS

• CVE-2026-8286: require a matching SSL configuration before reusing a pooled connection for a clear-text transfer that upgrades via STARTTLS

• CVE-2026-8286: require a matching SSL configuration before reusing a pooled connection for a clear-text transfer that upgrades via STARTTLS

• SECURITY UPDATE: stale custom cookie host causes cookie leak
  • debian/patches/CVE-2026-6276.patch: clear the remembered custom Host: name at the start of every request in lib/http.c.
  • CVE-2026-6276
• SECURITY UPDATE: wrong STARTTLS connection reuse
  • debian/patches/CVE-2026-8286.patch: require a matching SSL configuration when reusing a connection for a transfer that may upgrade to TLS in lib/url.c.
  • CVE-2026-8286
• SECURITY UPDATE: env-set cross-proxy Digest auth state leak
  • debian/patches/CVE-2026-8927.patch: flush the proxy Digest state when the proxy read from the environment changes in lib/url.c, lib/urldata.h.
  • CVE-2026-8927
• SECURITY UPDATE: incomplete mTLS config in connection reuse and TLS session cache
  • debian/patches/CVE-2026-8932.patch: include the client private key options in the primary SSL config so connection reuse and the TLS session cache compare them in lib/url.c, lib/urldata.h, lib/vtls/vtls.c.
  • CVE-2026-8932
• SECURITY UPDATE: HTTP/2 push headers memory leak
  • debian/patches/CVE-2024-2398.patch: free the whole set of push headers on the array-growth failure path in lib/http2.c.
  • CVE-2024-2398

• CVE-2026-8286: fix connection reuse for STARTTLS with mismatching TLS config

• SECURITY UPDATE: connection reuse with a mismatching TLS configuration for STARTTLS protocols
  • debian/patches/CVE-2026-8286.patch: also require a matching SSL configuration when looking for a connection to reuse for a transfer that may upgrade to TLS from a clear-text start in lib/url.c
  • CVE-2026-8286
• SECURITY UPDATE: connection reuse across different GSS-API service names
  • debian/patches/CVE-2026-8458.patch: keep the service name and the proxy service name on the connection and compare them when looking for a connection to reuse in lib/urldata.h, lib/url.c and lib/http_negotiate.c
  • CVE-2026-8458

A vulnerability exists where a new transfer that uses STARTTLS to upgrade the connection might reuse an existing live connection even though the TLS configuration mismatches so it should not.

These are all security issues fixed in the curl-8.21.0-1.1 package on the GA media of openSUSE Tumbleweed.

This update for curl fixes the following issues

• CVE-2026-8286: wrong STARTTLS connection reuse (bsc#1268402).
• CVE-2026-8458: wrong reuse for different services (bsc#1268407).
• CVE-2026-8924: traling dot domain super cookie (bsc#1268409).
• CVE-2026-8927: env-set cross-proxy Digest auth state leak (bsc#1268413).
• CVE-2026-9079: stale proxy password leak (bsc#1268415).
• CVE-2026-9080: UAF after pause in socket callback (bsc#1268416).
• CVE-2026-9545: exposing HTTP/3 early data (bsc#1268417).
• CVE-2026-9547: SSH improper host validation (bsc#1268420).
• CVE-2026-10536: HTTP/2 stream-dependency tree UAF (bsc#1268422).
• CVE-2026-12064: proto-default skips SSH verification (bsc#1268427).

Root has patched CVE-2026-8286 in the curl package for Root:Alpine:3.15. Multiple fixed versions available.

Root has patched CVE-2026-8286 in the curl package for Root:Alpine:3.17. Multiple fixed versions available.

Root has patched CVE-2026-8286 in the curl package for Root:Alpine:3.20. Multiple fixed versions available.

Root has patched CVE-2026-8286 in the curl package for Root:Alpine:3.21. Multiple fixed versions available.

Root has patched CVE-2026-8286 in the curl package for Root:Alpine:3.22. Multiple fixed versions available.

Root has patched CVE-2026-8286 in the curl package for Root:Alpine:3.23. Multiple fixed versions available.

Root has patched CVE-2026-8286 in the curl package for Root:Debian:11. Multiple fixed versions available.

Root has patched CVE-2026-8286 in the curl package for Root:Debian:12. Multiple fixed versions available.

Root has patched CVE-2026-8286 in the curl package for Root:Debian:13. Multiple fixed versions available.

This update for curl fixes the following issues

• CVE-2026-8286: wrong STARTTLS connection reuse (bsc#1268402).
• CVE-2026-8458: wrong reuse for different services (bsc#1268407).
• CVE-2026-8924: traling dot domain super cookie (bsc#1268409).
• CVE-2026-8927: env-set cross-proxy Digest auth state leak (bsc#1268413).
• CVE-2026-9079: stale proxy password leak (bsc#1268415).
• CVE-2026-9080: UAF after pause in socket callback (bsc#1268416).
• CVE-2026-9545: exposing HTTP/3 early data (bsc#1268417).
• CVE-2026-9547: SSH improper host validation (bsc#1268420).
• CVE-2026-10536: HTTP/2 stream-dependency tree UAF (bsc#1268422).
• CVE-2026-12064: proto-default skips SSH verification (bsc#1268427).

This update for curl fixes the following issues

• CVE-2026-8286: wrong STARTTLS connection reuse (bsc#1268402).
• CVE-2026-8458: wrong reuse for different services (bsc#1268407).
• CVE-2026-8924: traling dot domain super cookie (bsc#1268409).
• CVE-2026-8927: env-set cross-proxy Digest auth state leak (bsc#1268413).
• CVE-2026-9079: stale proxy password leak (bsc#1268415).
• CVE-2026-9080: UAF after pause in socket callback (bsc#1268416).
• CVE-2026-9545: exposing HTTP/3 early data (bsc#1268417).
• CVE-2026-9547: SSH improper host validation (bsc#1268420).
• CVE-2026-10536: HTTP/2 stream-dependency tree UAF (bsc#1268422).
• CVE-2026-12064: proto-default skips SSH verification (bsc#1268427).

This update for curl fixes the following issues

• CVE-2026-8286: wrong STARTTLS connection reuse (bsc#1268402).
• CVE-2026-8458: wrong reuse for different services (bsc#1268407).
• CVE-2026-8924: traling dot domain super cookie (bsc#1268409).
• CVE-2026-8927: env-set cross-proxy Digest auth state leak (bsc#1268413).
• CVE-2026-9079: stale proxy password leak (bsc#1268415).
• CVE-2026-9080: UAF after pause in socket callback (bsc#1268416).
• CVE-2026-9545: exposing HTTP/3 early data (bsc#1268417).
• CVE-2026-9547: SSH improper host validation (bsc#1268420).
• CVE-2026-10536: HTTP/2 stream-dependency tree UAF (bsc#1268422).
• CVE-2026-12064: proto-default skips SSH verification (bsc#1268427).

This update for curl fixes the following issues

• CVE-2026-8286: wrong STARTTLS connection reuse (bsc#1268402).
• CVE-2026-8458: wrong reuse for different services (bsc#1268407).
• CVE-2026-8924: traling dot domain super cookie (bsc#1268409).
• CVE-2026-8927: env-set cross-proxy Digest auth state leak (bsc#1268413).
• CVE-2026-9079: stale proxy password leak (bsc#1268415).
• CVE-2026-9080: UAF after pause in socket callback (bsc#1268416).
• CVE-2026-9545: exposing HTTP/3 early data (bsc#1268417).
• CVE-2026-9547: SSH improper host validation (bsc#1268420).
• CVE-2026-10536: HTTP/2 stream-dependency tree UAF (bsc#1268422).
• CVE-2026-12064: proto-default skips SSH verification (bsc#1268427).