PT-2021-3597 · Selinux+6 · Selinux+6

Nicolas Iooss · Published 2021-01-18 · Updated 2025-11-03 · CVE-2021-36084

Positive Technologies (AI Summary)

CVSS v3.1

3.3

Low

Base vector

AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L

Name of the Vulnerable Software and Affected Versions SELinux version 3.2

Description The issue is related to a use-after-free error in the cil verify classperms() function of the SELinux access control system. This error can be exploited to cause a denial of service. The cil verify classperms() function is called from cil verify classpermission and cil pre verify helper.

Recommendations For SELinux version 3.2, consider disabling the cil verify classperms() function as a temporary workaround until a patch is available. Restrict access to the affected components to minimize the risk of exploitation. At the moment, there is no information about a newer version that contains a fix for this vulnerability.

Exploit

Use After Free

Weakness Enumeration

CWE-416

Related Identifiers

ALSA-2021:4513

BDU:2021-03701

CESA-2021_4513

CVE-2021-36084

DLA-3930-1

RHSA-2021:4513

RHSA-2021_4513

RLSA-2021:4513

USN-5391-1

Affected Products

Almalinux

Centos

Linuxmint

Red Hat

Rocky Linux

Selinux

Ubuntu

References · 36

• 🔥 https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=31065 · Exploit
• https://github.com/SELinuxProject/selinux/commit/f34d3d30c8325e4847a6b696fe7a3936a8a361f3 · Patch
• https://ubuntu.com/security/CVE-2021-36087 · Vendor Advisory
• https://ubuntu.com/security/CVE-2021-36086 · Vendor Advisory
• https://osv.dev/vulnerability/USN-5391-1 · Vendor Advisory
• https://osv.dev/vulnerability/UBUNTU-CVE-2021-36084 · Vendor Advisory
• https://osv.dev/vulnerability/DEBIAN-CVE-2021-36084 · Vendor Advisory
• https://osv.dev/vulnerability/ALSA-2021:4513 · Vendor Advisory
• https://security-tracker.debian.org/tracker/CVE-2021-36084 · Vendor Advisory
• https://linux.oracle.com/errata/ELSA-2021-4513.html · Vendor Advisory
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/U7ZYR3PIJ75N6U2IONJWCKZ5L2NKJTGR · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2021-36084 · Security Note
• https://osv.dev/vulnerability/DLA-3930-1 · Vendor Advisory
• https://cve.org/CVERecord?id=CVE-2021-36084 · Security Note
• https://ubuntu.com/security/CVE-2021-36084 · Vendor Advisory