Medium [CVE-2026-63381] Memory corruption due to use-after-free
This medium-severity Red Hat Linux advisory covers CVE-2026-63381 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Cert Manager support for Red Hat OpenShift release 1.20.
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Summary
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 can lead to a dangling pointer, which an attacker could exploit to cause memory corruption or crash the application.
Red Hat Enterprise Linux, OpenShift (RHCOS), RHIVOS, and community products (Fedora, Hummingbird) ship affected versions of libevent. Red Hat severity: Moderate — CVSS 6.6 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:H).
Weakness: CWE-825. Affected Red Hat products: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 9; Cert Manager support for Red Hat OpenShift release 1.20; Red Hat Hardened Images; Red Hat Update Infrastructure 5; Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 7; Red Hat Enterprise Linux 8; Red Hat OpenShift Container Platform 4.
Will not fix / out of support: Red Hat Enterprise Linux 6.
Affected products named by the advisory: Red Hat package: libevent2.
- < 2.1.13
- < 2.2.2-alpha
Official advisory · high-confidence parse· fetched 14 days ago·verify at source
- 2.1.13
- 2.2.2
- libevent-0:2.1.13-1.el10_2
- libevent-0:2.1.13-1.el9_8
- cert-manager/jetstack-cert-manager-rhel9:1790223279
- cert-manager/cert-manager-istio-csr-rhel9:1790223719
- cert-manager/cert-manager-operator-rhel9:1790272426
- cert-manager/jetstack-cert-manager-acmesolver-rhel9:1790589998
- cert-manager/jetstack-cert-manager-rhel9:1790589912
- cert-manager/cert-manager-istio-csr-rhel9:1790589914
- cert-manager/cert-manager-operator-rhel9:1790589855
- libevent-main-2.1.12-19.1.hum1
- rhui5/cds-kubernetes-rhel9:1790241897
- rhui5/cds-rhel9:1790241954
- rhui5/haproxy-rhel9:1790241900
- rhui5/installer-rhel9:1790241922
- rhui5/rhua-rhel9:1790242004
- RHSA-2026:67909
- RHSA-2026:67910
- RHSA-2026:72394
- RHSA-2026:72395
- RHSA-2026:72399
- RHSA-2026:72470
- RHSA-2026:72475
- RHSA-2026:72476
- RHSA-2026:60853
- RHSA-2026:71603
Official advisory · high-confidence parse· fetched 14 days ago·verify at source
Mitigation checklist
- Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.
Official advisory · high-confidence parse· fetched 14 days ago·verify at source
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