CVE-2021-3493

unknown KEV

Published 2022-10-20 · Modified 2022-10-20

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CVSS v3

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CVSS v4 NEW

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not yet in upstream

VIR risk

2.5

Description

The overlayfs stacking file system in Linux kernel does not properly validate the application of file capabilities against user namespaces, which could lead to privilege escalation.

CISA KEV

Vendor: Linux
Product: Kernel
Due date: 2022-11-10

Predictions

Exploit likelihood

99%

Patch ETA

—

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

No mitigations published for this CVE yet.

The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.

✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here with source_tier=community-verified.

Exploits

Public proof-of-concept code below. AS-IS, for defenders and authorised testing only.

Metasploit modules

exploit_linux/local/cve_2021_3493_overlayfs rank 500

2021 Ubuntu Overlayfs LPE

Source fetch failed: fetch_error — view the original via the link above.

OS impact

SUSE Affected 1 release

Version	Status	Fixed in
—	Affected	—

Debian Fixed 5 releases

Version	Status	Fixed in
trixie	Fixed	`5.10.38-1`
sid	Fixed	`5.10.38-1`
forky	Fixed	`5.10.38-1`
bullseye	Fixed	`5.10.38-1`
bookworm	Fixed	`5.10.38-1`

References

Community-verified mitigations for this CVE will appear above when contributors publish them.

Verify integrity in audit chain (admin only). AS-IS.