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Vulnerability record · CVE-2026-63383 · published 20 August 2026

CVE-2026-63383: Out-of-bounds read vulnerability

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.

8.7 CVSS 4.0 High EPSS 0.52% · top 57.9% CWE-125 · Out-of-bounds read Awaiting Analysis
8.7CVSS 4.0 base score
0.52%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
6References
9 Sep 2026Last modified by NVD

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.

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

References

LinkTags
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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Source: NIST National Vulnerability Database (record CVE-2026-63383), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.