What’s Vulnerable › Vulnerabilities

CVE-2026-63383: Libevent: decode_tag_internal() can lead to out-of-bounds read

• Severity: high (CVSS 8.7 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-20 · updated 2026-10-26
• Weakness: CWE-125

Description

Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent can read beyond a contiguous evbuffer region in event_tagging.c when decode_tag_internal requests at most five bytes from evbuffer_pullup but iterates using the full logical buffer length. A fragmented evbuffer containing a six-byte malformed tag can therefore advance past the pullup window and trigger an out-of-bounds read, which can crash a process that decodes attacker-controlled tagged RPC data. This issue is fixed in versions 2.1.13 and 2.2.2-alpha.

Affected products

• libevent: from 2.2.0-alpha, < 2.2.2-alpha; before 2.1.13

References

• https://github.com/libevent/libevent/commit/91ed8745eebabdd27592a83d350338a8c4626321
• https://github.com/libevent/libevent/commit/e1f9e21887c6b104e206a718385ba3ffc75180cb
• https://github.com/libevent/libevent/releases/tag/release-2.1.13-stable
• https://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha
• https://github.com/libevent/libevent/security/advisories/GHSA-fj29-64w6-73h6
• https://github.com/libevent/libevent/security/advisories/GHSA-fj29-64w6-73h6

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