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CVE-2026-63381

Updated on 20 Aug 2026

Severity

5.8 Medium severity

Details

CVSS score
5.8
CVSS vector
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
CWE ID
Links
NISTCIRCLRHELUbuntu

Overview

About vulnerability

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.

Details

Affected product:
AlmaLinux 9.2 ESU , Alpine Linux 3.23 , Alpine Linux 3.24 , Amazon Linux 2 ELS , CentOS 6 ELS , CentOS 7 ELS , CloudLinux 7 ELS , Debian 11 ELS , Debian 12 , Debian 13 , Oracle Linux 6 ELS , Oracle Linux 7 ELS , RHEL 7 ELS , TuxCare 9.6 ESU , TuxCare 9.8 ESU , Ubuntu 18.04 ELS
Affected packages:
libevent @ 2.1.12 (+15 more)

Fixes