CVE-2021-0920 — Android Kernel Race Condition Vulnerability

In unix_scm_to_skb of af_unix.c, there is a possible use after free bug due to a race condition. This could lead to local escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android kernelAndro

01What is this vulnerability?

In unix_scm_to_skb of af_unix.c, there is a possible use after free bug due to a race condition. This could lead to local escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android kernelAndroid ID: A-196926917References: Upstream kernel

02Affected products

Vendor	Product	Versions
n	a / Android	Android kernel

03Active exploitation status

Yes — actively exploited. Added to the CISA KEV catalog on 2022-05-23. Ransomware use: Unknown.

04Recommended remediation

• Patch to a fixed version listed in the vendor advisory (see references below).
• Mitigate with WAF rules, network egress filters, or feature flags where the patch is not yet available.
• Hunt historical logs for exploitation indicators — see Detection signatures below.

05Technical details

For the full vendor write-up, exploit chains, and reference implementations, see the references list in section 09.

06Detection signatures

Open the Sigma generator with a pre-filled prompt for this CVE to draft a starting detection in your stack of choice:

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07Related CVEs

No directly-cited follow-up CVEs in the KB record for this advisory. The references list in section 09 carries the vendor cross-references.

08Timeline

• Published: 2021-12-15T18:05:31.000Z
• Last modified: 2025-10-21T23:15:50.498Z
• Added to CISA KEV: 2022-05-23
• BOD 22-01 due: 2022-06-13

09References

• source.android.com — https://source.android.com/security/bulletin/2021-11-01
• lists.debian.org — https://lists.debian.org/debian-lts-announce/2021/12/msg00012.html