CVE-2021-4155

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2022-08-24 · updated 2026-06-17
Weakness: CWE-131

Description

A data leak flaw was found in the way XFS_IOC_ALLOCSP IOCTL in the XFS filesystem allowed for size increase of files with unaligned size. A local attacker could use this flaw to leak data on the XFS filesystem otherwise not accessible to them.

Affected products

Linux kernel: before 5.16 — fixed in 5.16

How to fix

Upgrade to a fixed version: Linux kernel 5.16. Check the vendor advisory for mitigations.

References

https://access.redhat.com/security/cve/CVE-2021-4155
https://bugzilla.redhat.com/show_bug.cgi?id=2034813
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=983d8e60f50806f90534cc5373d0ce867e5aaf79
https://security-tracker.debian.org/tracker/CVE-2021-4155
https://www.openwall.com/lists/oss-security/2022/01/10/1
https://access.redhat.com/security/cve/CVE-2021-4155
https://bugzilla.redhat.com/show_bug.cgi?id=2034813
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=983d8e60f50806f90534cc5373d0ce867e5aaf79
https://security-tracker.debian.org/tracker/CVE-2021-4155
https://www.openwall.com/lists/oss-security/2022/01/10/1

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