CVE-2020-11935 — It was discovered that aufs improperly managed inode reference counts in the vfs

It was discovered that aufs improperly managed inode reference counts in the vfsub_dentry_open() method. A local attacker could use this vulnerability to cause a denial of service attack.

01What is this vulnerability?

It was discovered that aufs improperly managed inode reference counts in the vfsub_dentry_open() method. A local attacker could use this vulnerability to cause a denial of service attack.

02Affected products

Vendor	Product	Versions
Ubuntu	Linux kernel (aufs filesystem module)	4.4.0-186.216, 4.15.0-112.113, 5.4.0-42.46

03Active exploitation status

Not currently listed on the CISA Known Exploited Vulnerabilities (KEV) catalog. EPSS is the best forward-looking signal — see the EPSS row above.

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

Ask SARA in chat to draft a starting detection for this CVE in your stack of choice.

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: 2023-04-07T00:00:00.000Z
• Last modified: 2024-08-04T11:42:00.593Z

09References

• ubuntu.com — https://ubuntu.com/security/CVE-2020-11935
• bugs.launchpad.net — https://bugs.launchpad.net/bugs/1873074