CVE-2026-63388

Libevent additionally provides a sophisticated framework for buffered network IO, with support for sockets, filters, rate-limiting, SSL, zero-copy file transmission, and IOCP. Libevent includes support for several useful protocols, including DNS, HTTP, and a minimal RPC framewor.

Security Fix(es):

The updated packages fix some security vulnerabilities. libevent is a lightweight event notification library used for handling event loops and callback mechanisms, widely used in network applications.(CVE-2026-63379)

The updated packages fix some security vulnerabilities affecting the libevent library.(CVE-2026-63381)

The updated packages fix some security vulnerabilities.(CVE-2026-63382)

The updated packages fix some security vulnerabilities.(CVE-2026-63383)

The updated packages fix some security vulnerabilities.(CVE-2026-63384)

The updated packages fix some security vulnerabilities.(CVE-2026-63385)

The updated packages fix some security vulnerabilities.(CVE-2026-63387)

The updated packages fix some security vulnerabilities.(CVE-2026-63388)

The libevent packages provide an abstract asynchronous event notification library.

Security Fix(es):

• libevent: Libevent: Denial of Service via malformed RPC data (CVE-2026-63383)

• libevent: Libevent: Off-by-one stack buffer overflow leading to denial of service or data corruption (CVE-2026-63387)

• libevent: Libevent: Denial of Service via integer conversion error in evtag_unmarshal_header (CVE-2026-63384)

• libevent evhttp: Multiple HTTP Parser Bugs Enable Request Smuggling (CVE-2026-63382)

• libevent: Libevent: Arbitrary code execution via heap out-of-bounds write in AF_UNIX handling (CVE-2026-63388)

• libevent: Libevent: HTTP header handling bugs create risk of access control bypass. (CVE-2026-63385)

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 libevent packages provide an abstract asynchronous event notification library.

Security Fix(es):

• libevent: Libevent: Denial of Service via malformed RPC data (CVE-2026-63383)

• libevent: Libevent: Off-by-one stack buffer overflow leading to denial of service or data corruption (CVE-2026-63387)

• libevent: Libevent: Memory corruption due to use-after-free (CVE-2026-63381)

• libevent: Libevent: Denial of Service via integer conversion error in evtag_unmarshal_header (CVE-2026-63384)

• libevent evhttp: Multiple HTTP Parser Bugs Enable Request Smuggling (CVE-2026-63382)

• libevent: Libevent: Arbitrary code execution via heap out-of-bounds write in AF_UNIX handling (CVE-2026-63388)

• libevent: Libevent: HTTP header handling bugs create risk of access control bypass. (CVE-2026-63385)

• libevent: Libevent: HTTP header smuggling allows authorization bypass or cache poisoning (CVE-2026-63379)

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 libevent packages provide an abstract asynchronous event notification library.

Security Fix(es):

• libevent: Libevent: Denial of Service via malformed RPC data (CVE-2026-63383)

• libevent: Libevent: Off-by-one stack buffer overflow leading to denial of service or data corruption (CVE-2026-63387)

• libevent: Libevent: Memory corruption due to use-after-free (CVE-2026-63381)

• libevent: Libevent: Denial of Service via integer conversion error in evtag_unmarshal_header (CVE-2026-63384)

• libevent evhttp: Multiple HTTP Parser Bugs Enable Request Smuggling (CVE-2026-63382)

• libevent: Libevent: Arbitrary code execution via heap out-of-bounds write in AF_UNIX handling (CVE-2026-63388)

• libevent: Libevent: HTTP header handling bugs create risk of access control bypass. (CVE-2026-63385)

• libevent: Libevent: HTTP header smuggling allows authorization bypass or cache poisoning (CVE-2026-63379)

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.

Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent has a heap out-of-bounds write in bufferevent_sock.c when bufferevent_socket_set_conn_address_ copies a kernel-supplied AF_UNIX peer address into bufferevent_private.conn_address. Release builds compiled with NDEBUG disable the EVUTIL_ASSERT length guard, and the evhttp accept path can pass a 110-byte sockaddr from accept() into the 28-byte field. An unauthenticated local peer able to connect to an AF_UNIX listener can overwrite the adjacent dns_request pointer and heap data, causing memory corruption with confidentiality, integrity, and availability impact. This issue is fixed in versions 2.1.13 and 2.2.2-alpha.

The libevent packages provide an abstract asynchronous event notification library.

Security Fix(es):

• libevent: Libevent: Denial of Service via malformed RPC data (CVE-2026-63383)
• libevent: Libevent: Off-by-one stack buffer overflow leading to denial of service or data corruption (CVE-2026-63387)
• libevent: Libevent: Denial of Service via integer conversion error in evtag_unmarshal_header (CVE-2026-63384)
• libevent evhttp: Multiple HTTP Parser Bugs Enable Request Smuggling (CVE-2026-63382)
• libevent: Libevent: Arbitrary code execution via heap out-of-bounds write in AF_UNIX handling (CVE-2026-63388)
• libevent: Libevent: HTTP header handling bugs create risk of access control bypass. (CVE-2026-63385)

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 libevent packages provide an abstract asynchronous event notification library.

Security Fix(es):

• libevent: Libevent: Denial of Service via malformed RPC data (CVE-2026-63383)
• libevent: Libevent: Off-by-one stack buffer overflow leading to denial of service or data corruption (CVE-2026-63387)
• libevent: Libevent: Memory corruption due to use-after-free (CVE-2026-63381)
• libevent: Libevent: Denial of Service via integer conversion error in evtag_unmarshal_header (CVE-2026-63384)
• libevent evhttp: Multiple HTTP Parser Bugs Enable Request Smuggling (CVE-2026-63382)
• libevent: Libevent: Arbitrary code execution via heap out-of-bounds write in AF_UNIX handling (CVE-2026-63388)
• libevent: Libevent: HTTP header handling bugs create risk of access control bypass. (CVE-2026-63385)
• libevent: Libevent: HTTP header smuggling allows authorization bypass or cache poisoning (CVE-2026-63379)

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 libevent packages provide an abstract asynchronous event notification library.

Security Fix(es):

• libevent: Libevent: Denial of Service via malformed RPC data (CVE-2026-63383)
• libevent: Libevent: Off-by-one stack buffer overflow leading to denial of service or data corruption (CVE-2026-63387)
• libevent: Libevent: Memory corruption due to use-after-free (CVE-2026-63381)
• libevent: Libevent: Denial of Service via integer conversion error in evtag_unmarshal_header (CVE-2026-63384)
• libevent evhttp: Multiple HTTP Parser Bugs Enable Request Smuggling (CVE-2026-63382)
• libevent: Libevent: Arbitrary code execution via heap out-of-bounds write in AF_UNIX handling (CVE-2026-63388)
• libevent: Libevent: HTTP header handling bugs create risk of access control bypass. (CVE-2026-63385)
• libevent: Libevent: HTTP header smuggling allows authorization bypass or cache poisoning (CVE-2026-63379)

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.

Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent has a heap out-of-bounds write in bufferevent_sock.c when bufferevent_socket_set_conn_address_ copies a kernel-supplied AF_UNIX peer address into bufferevent_private.conn_address. Release builds compiled with NDEBUG disable the EVUTIL_ASSERT length guard, and the evhttp accept path can pass a 110-byte sockaddr from accept() into the 28-byte field. An unauthenticated local peer able to connect to an AF_UNIX listener can overwrite the adjacent dns_request pointer and heap data, causing memory corruption with confidentiality, integrity, and availability impact. This issue is fixed in versions 2.1.13 and 2.2.2-alpha.

Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent has a heap out-of-bounds write in bufferevent_sock.c when bufferevent_socket_set_conn_address_ copies a kernel-supplied AF_UNIX peer address into bufferevent_private.conn_address. Release builds compiled with NDEBUG disable the EVUTIL_ASSERT length guard, and the evhttp accept path can pass a 110-byte sockaddr from accept() into the 28-byte field. An unauthenticated local peer able to connect to an AF_UNIX listener can overwrite the adjacent dns_request pointer and heap data, causing memory corruption with confidentiality, integrity, and availability impact. This issue is fixed in versions 2.1.13 and 2.2.2-alpha.

Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent has a heap out-of-bounds write in bufferevent_sock.c when bufferevent_socket_set_conn_address_ copies a kernel-supplied AF_UNIX peer address into bufferevent_private.conn_address. Release builds compiled with NDEBUG disable the EVUTIL_ASSERT length guard, and the evhttp accept path can pass a 110-byte sockaddr from accept() into the 28-byte field. An unauthenticated local peer able to connect to an AF_UNIX listener can overwrite the adjacent dns_request pointer and heap data, causing memory corruption with confidentiality, integrity, and availability impact. This issue is fixed in versions 2.1.13 and 2.2.2-alpha.

Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent has a heap out-of-bounds write in bufferevent_sock.c when bufferevent_socket_set_conn_address_ copies a kernel-supplied AF_UNIX peer address into bufferevent_private.conn_address. Release builds compiled with NDEBUG disable the EVUTIL_ASSERT length guard, and the evhttp accept path can pass a 110-byte sockaddr from accept() into the 28-byte field. An unauthenticated local peer able to connect to an AF_UNIX listener can overwrite the adjacent dns_request pointer and heap data, causing memory corruption with confidentiality, integrity, and availability impact. This issue is fixed in versions 2.1.13 and 2.2.2-alpha.

The updated packages fix some security vulnerabilities.

These are all security issues fixed in the libevent-2_1-7-2.1.13-1.1 package on the GA media of openSUSE Tumbleweed.

Root has patched CVE-2026-63388 in the libevent package for Root:Debian:11. Multiple fixed versions available.

Root has patched CVE-2026-63388 in the libevent package for Root:Debian:12. Multiple fixed versions available.

Root has patched CVE-2026-63388 in the libevent package for Root:Debian:13. Multiple fixed versions available.

Michał Majchrowicz and Marcin Wyczechowski discovered that libevent incorrectly handled certain DNS responses. A remote attacker could possibly use this issue to cause a denial of service or execute arbitrary code. (CVE-2026-63387)

It was discovered that libevent incorrectly handled certain connections. A local attacker could possibly use this issue to cause a denial of service or execute arbitrary code. This issue only affected Ubuntu 18.04 LTS, Ubuntu 20.04 LTS, Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, and Ubuntu 26.04 LTS. (CVE-2026-63388)