#VU62663 Out-of-bounds read in selinux - CVE-2021-36087

Vulnerability identifier: #VU62663

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-2021-36087

CWE-ID: CWE-125

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 boundary error in the ebitmap_match_any() function within the CIL compiler in SELinux. A local user can trigger an out-of-bounds read error and perform denial of service attack.

Mitigation
Install update 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-2021-585.yaml
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=32675
https://lore.kernel.org/selinux/CAEN2sdqJKHvDzPnxS-J8grU8fSf32DDtx=kyh84OsCq_Vm+yaQ@mail.gmail.com/T/
https://github.com/SELinuxProject/selinux/commit/340f0eb7f3673e8aacaf0a96cbfcd4d12a405521
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.