CVE-2026-63383
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.
What this means for your business
- FIRST's prediction model gives it a 0.5% chance of attack attempts being seen in the next 30 days, ranking above 41% of all known flaws.
What to do
- 1Ask your IT team or provider whether any of your systems use the affected product.
- 2If you do, follow the vendor's guidance. No patch reference has been published yet.
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Scoring
- CVSS
- Not yet scored
- CVSS v4
- 8.7
- Weakness
- CWE-125
- Assigned by
- security-advisories@github.com
Dates
- Published
- 2026-08-20
- Last modified
- 2026-09-09
- Sources
- NVD
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