#VU62661 Use-after-free in selinux - CVE-2021-36085

Vulnerability identifier: #VU62661

Vulnerability risk: Low

CVSSv4.0: 1.1 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2021-36085

CWE-ID: CWE-416

Exploitation vector: Local

Exploit availability: No

Vulnerable software:
selinux
Other software / Other software solutions

Vendor: SELinux Project

Description

The vulnerability allows a local user to perform a denial of service (DoS) attack.

The vulnerability exists due to a use-after-free error within the __cil_verify_classperms() function in CIL compiler in SELinux. A local user can perform a denial of service (DoS) attack.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

selinux: before 3.3

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External links
https://github.com/google/oss-fuzz-vulns/blob/main/vulns/selinux/OSV-2021-421.yaml
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=31124
https://github.com/SELinuxProject/selinux/commit/2d35fcc7e9e976a2346b1de20e54f8663e8a6cba
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/U7ZYR3PIJ75N6U2IONJWCKZ5L2NKJTGR/

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Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.