CVE-2026-63381
MEDIUMDescription
Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent has a use-after-free in buffer.c when evbuffer_add_buffer_reference processes an output buffer whose out_total_len is zero. evbuffer_free_all_chains frees the initial empty chain without resetting outbuf->first, outbuf->last, or outbuf->last_with_datap, and APPEND_CHAIN_MULTICAST subsequently dereferences the dangling chain pointer. A caller that can drive this buffer state can cause memory corruption or a process crash. This issue is fixed in versions 2.1.13 and 2.2.2-alpha.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v4 Vector
Exploitability
Impact
CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/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:X/V:X/RE:X/U:X
Exploit Intelligence
Low risk: more likely to be exploited than 2% of all known CVEs.
References
Related Vulnerabilities
Other CWE-908 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2025-5777 | High | 7.5 | 100% | KEV + Ransom | Fix |
| CVE-2023-24941 | Critical | 9.8 | 95% | - | Fix |
| CVE-2007-1751 | High | 9.3 | 61% | - | - |
| CVE-2008-0081 | Critical | 9.8 | 58% | - | - |
| CVE-2020-1934 | Medium | 5.3 | 52% | - | Fix |
| CVE-2011-1255 | High | 9.3 | 42% | - | - |
Common questions
How do I fix CVE-2026-63381?
Published advisories record a fix for 3 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.
Is CVE-2026-63381 being actively exploited?
Not that we know of. CVE-2026-63381 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.12% is the estimated probability that it will be exploited in the next 30 days. That is higher than 2% of all scored CVEs.
How severe is CVE-2026-63381?
CVE-2026-63381 has a CVSS v4 base score of 5.8, rated moderate. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-63381 affect?
Published advisories record a fix for libevent (Debian), libevent (Red Hat / RHEL), libevent (Rocky). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-08-21.