CVE-2026-63381
Libevent: Dangling Pointer in `evbuffer_add_buffer_reference`
CVE-2026-63381 is fixed in 20 products on 1 platform, first by libevent-2.1-7t64 2.1.12-stable-10ubuntu0.1, released August 20, 2026. It is not reported as exploited. Patch Radar priority: High.
High
CVSS
8.6
Moderate
Exploitation
None reported
No vendor assessment
CISA KEV
Not listed
Not in the Known Exploited Vulnerabilities catalog
EPSS
0.0012
1st percentile
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.
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Linux | |||
| libevent · Debian 12.15 (bookworm) | 2.1.12-stable-8+deb12u1 | DEBIAN-CVE-2026-63381 | Aug 21, 2026 |
| libevent · Debian 13.5 (trixie) | 2.1.13-stable-1~deb13u1 | DEBIAN-CVE-2026-63381 | Aug 21, 2026 |
| libevent · Debian 14 | 2.1.13-stable-1 | DEBIAN-CVE-2026-63381 | Aug 21, 2026 |
| libevent · Fedora 43 | 2.1.13-1.fc43 | FEDORA-2026-728DD9F704 | Sep 7, 2026 |
| libevent · RHEL 10 | 2.1.13-1.el10_2 | RHSA-2026:67909 | Sep 17, 2026 |
| libevent · RHEL 9 | 0:2.1.13-1.el9_8 | RHSA-2026:67910 | Sep 19, 2026 |
| libevent · almalinux 10 | 2.1.13-1.el10_2 | ALSA-2026:67909 | Sep 16, 2026 |
| libevent · almalinux 9 | 2.1.13-1.el9_8 | ALSA-2026:67910 | Sep 16, 2026 |
| libevent · ol 10 | 0:2.1.13-1.el10_2 | ELSA-2026-67909 | Sep 16, 2026 |
| libevent · ol 9 | 0:2.1.13-1.el9_8 | ELSA-2026-67910 | Sep 16, 2026 |
| libevent · rocky 10 | 0:2.1.13-1.el10_2 | RLSA-2026:67909 | Sep 17, 2026 |
| libevent · rocky 9 | 0:2.1.13-1.el9_8 | RLSA-2026:67910 | Sep 17, 2026 |
| libevent-2.1-6 · Ubuntu 18.04.6 LTS (bionic) | 2.1.8-stable-4ubuntu0.1~esm1 | libevent-2.1-6 2.1.8-stable-4ubuntu0.1~esm1 | Sep 3, 2026 |
| libevent-2.1-7 · Ubuntu 20.04 LTS (focal) | 2.1.11-stable-1ubuntu0.1~esm1 | libevent-2.1-7 2.1.11-stable-1ubuntu0.1~esm1 | Sep 3, 2026 |
| libevent-2.1-7 · Ubuntu 22.04.1 LTS (jammy) | 2.1.12-stable-1ubuntu0.1 | libevent-2.1-7 2.1.12-stable-1ubuntu0.1 | Sep 3, 2026 |
| libevent-2.1-7t64 · Ubuntu 24.04.5 LTS (noble) | 2.1.12-stable-9ubuntu2.1 | libevent-2.1-7t64 2.1.12-stable-9ubuntu2.1 | Sep 3, 2026 |
| libevent-2.1-7t64 · Ubuntu 26.04.1 LTS (resolute) | 2.1.12-stable-10ubuntu0.1 | libevent-2.1-7t64 2.1.12-stable-10ubuntu0.1 | Aug 20, 2026 |
| libevent-core-2.1-6 · Ubuntu 18.04.6 LTS (bionic) | 2.1.8-stable-4ubuntu0.1~esm1 | libevent-core-2.1-6 2.1.8-stable-4ubuntu0.1~esm1 | Sep 3, 2026 |
| libevent-core-2.1-7 · Ubuntu 20.04 LTS (focal) | 2.1.11-stable-1ubuntu0.1~esm1 | libevent-core-2.1-7 2.1.11-stable-1ubuntu0.1~esm1 | Sep 3, 2026 |
| libevent-core-2.1-7 · Ubuntu 22.04.1 LTS (jammy) | 2.1.12-stable-1ubuntu0.1 | libevent-core-2.1-7 2.1.12-stable-1ubuntu0.1 | Sep 3, 2026 |
| libevent-core-2.1-7t64 · Ubuntu 24.04.5 LTS (noble) | 2.1.12-stable-9ubuntu2.1 | libevent-core-2.1-7t64 2.1.12-stable-9ubuntu2.1 | Sep 3, 2026 |
| libevent-core-2.1-7t64 · Ubuntu 26.04.1 LTS (resolute) | 2.1.12-stable-10ubuntu0.1 | libevent-core-2.1-7t64 2.1.12-stable-10ubuntu0.1 | Aug 20, 2026 |
| libevent-debuginfo · Fedora 43 | 2.1.13-1.fc43 | FEDORA-2026-728DD9F704 | Sep 7, 2026 |
| libevent-debugsource · Fedora 43 | 2.1.13-1.fc43 | FEDORA-2026-728DD9F704 | Sep 7, 2026 |
| libevent-devel · Fedora 43 | 2.1.13-1.fc43 | FEDORA-2026-728DD9F704 | Sep 7, 2026 |
| libevent-devel · RHEL 9 | 0:2.1.13-1.el9_8 | RHSA-2026:67910 | Sep 19, 2026 |
| libevent-devel · almalinux 10 | 2.1.13-1.el10_2 | ALSA-2026:67909 | Sep 16, 2026 |
| libevent-devel · almalinux 9 | 2.1.13-1.el9_8 | ALSA-2026:67910 | Sep 16, 2026 |
| libevent-devel · ol 10 | 0:2.1.13-1.el10_2 | ELSA-2026-67909 | Sep 16, 2026 |
| libevent-devel · ol 9 | 0:2.1.13-1.el9_8 | ELSA-2026-67910 | Sep 16, 2026 |
| libevent-doc · Fedora 43 | 2.1.13-1.fc43 | FEDORA-2026-728DD9F704 | Sep 7, 2026 |
| libevent-doc · RHEL 9 | 0:2.1.13-1.el9_8 | RHSA-2026:67910 | Sep 19, 2026 |
| libevent-doc · almalinux 10 | 2.1.13-1.el10_2 | ALSA-2026:67909 | Sep 16, 2026 |
| libevent-doc · almalinux 9 | 2.1.13-1.el9_8 | ALSA-2026:67910 | Sep 16, 2026 |
| libevent-doc · ol 10 | 0:2.1.13-1.el10_2 | ELSA-2026-67909 | Sep 16, 2026 |
| libevent-doc · ol 9 | 0:2.1.13-1.el9_8 | ELSA-2026-67910 | Sep 16, 2026 |
| libevent-extra-2.1-6 · Ubuntu 18.04.6 LTS (bionic) | 2.1.8-stable-4ubuntu0.1~esm1 | libevent-extra-2.1-6 2.1.8-stable-4ubuntu0.1~esm1 | Sep 3, 2026 |
| libevent-extra-2.1-7 · Ubuntu 20.04 LTS (focal) | 2.1.11-stable-1ubuntu0.1~esm1 | libevent-extra-2.1-7 2.1.11-stable-1ubuntu0.1~esm1 | Sep 3, 2026 |
| libevent-extra-2.1-7 · Ubuntu 22.04.1 LTS (jammy) | 2.1.12-stable-1ubuntu0.1 | libevent-extra-2.1-7 2.1.12-stable-1ubuntu0.1 | Sep 3, 2026 |
| libevent-extra-2.1-7t64 · Ubuntu 24.04.5 LTS (noble) | 2.1.12-stable-9ubuntu2.1 | libevent-extra-2.1-7t64 2.1.12-stable-9ubuntu2.1 | Sep 3, 2026 |
| libevent-extra-2.1-7t64 · Ubuntu 26.04.1 LTS (resolute) | 2.1.12-stable-10ubuntu0.1 | libevent-extra-2.1-7t64 2.1.12-stable-10ubuntu0.1 | Aug 20, 2026 |
| libevent-openssl-2.1-6 · Ubuntu 18.04.6 LTS (bionic) | 2.1.8-stable-4ubuntu0.1~esm1 | libevent-openssl-2.1-6 2.1.8-stable-4ubuntu0.1~esm1 | Sep 3, 2026 |
| libevent-openssl-2.1-7 · Ubuntu 20.04 LTS (focal) | 2.1.11-stable-1ubuntu0.1~esm1 | libevent-openssl-2.1-7 2.1.11-stable-1ubuntu0.1~esm1 | Sep 3, 2026 |
| libevent-openssl-2.1-7 · Ubuntu 22.04.1 LTS (jammy) | 2.1.12-stable-1ubuntu0.1 | libevent-openssl-2.1-7 2.1.12-stable-1ubuntu0.1 | Sep 3, 2026 |
| libevent-openssl-2.1-7t64 · Ubuntu 24.04.5 LTS (noble) | 2.1.12-stable-9ubuntu2.1 | libevent-openssl-2.1-7t64 2.1.12-stable-9ubuntu2.1 | Sep 3, 2026 |
| libevent-openssl-2.1-7t64 · Ubuntu 26.04.1 LTS (resolute) | 2.1.12-stable-10ubuntu0.1 | libevent-openssl-2.1-7t64 2.1.12-stable-10ubuntu0.1 | Aug 20, 2026 |
| libevent-pthreads-2.1-6 · Ubuntu 18.04.6 LTS (bionic) | 2.1.8-stable-4ubuntu0.1~esm1 | libevent-pthreads-2.1-6 2.1.8-stable-4ubuntu0.1~esm1 | Sep 3, 2026 |
| libevent-pthreads-2.1-7 · Ubuntu 20.04 LTS (focal) | 2.1.11-stable-1ubuntu0.1~esm1 | libevent-pthreads-2.1-7 2.1.11-stable-1ubuntu0.1~esm1 | Sep 3, 2026 |
| libevent-pthreads-2.1-7 · Ubuntu 22.04.1 LTS (jammy) | 2.1.12-stable-1ubuntu0.1 | libevent-pthreads-2.1-7 2.1.12-stable-1ubuntu0.1 | Sep 3, 2026 |
| libevent-pthreads-2.1-7t64 · Ubuntu 24.04.5 LTS (noble) | 2.1.12-stable-9ubuntu2.1 | libevent-pthreads-2.1-7t64 2.1.12-stable-9ubuntu2.1 | Sep 3, 2026 |
| libevent-pthreads-2.1-7t64 · Ubuntu 26.04.1 LTS (resolute) | 2.1.12-stable-10ubuntu0.1 | libevent-pthreads-2.1-7t64 2.1.12-stable-10ubuntu0.1 | Aug 20, 2026 |
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