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VulnerabilityPublished Updated

CVE-2025-21853: Linux kernel · bpf: avoid holding freeze_mutex during mmap operation

Affects Linux kernelSource GCVE Database

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Authoritative record:CVE-2025-21853· Medium

Not known to be exploited · CVSS 5.5 Medium · fixed in 5.15.0-1088.95~20.04.1 : update Linux kernel when convenient.

Data as of 12 Nov 2026, 19:33 UTC

CVSS 3.1 base score
5.5Medium
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
Patch
Available – fixed in 5.15.0-1088.95~20.04.1, 5.15.0-1094.103~20.04.1, 5.15.0-1087.96~20.04.2 +60
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 12 Mar 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 12 Nov 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
Ubuntu 24.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=nobleOther threatsAffected
  • <6.8.0-78.78
Fixed in
  • 6.8.0-78.78
Ubuntu 24.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=nobleOther threatsAffected
  • <6.8.0-1035.37
Fixed in
  • 6.8.0-1035.37
Ubuntu 24.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=nobleOther threatsAffected
  • <6.8.0-1034.39
Fixed in
  • 6.8.0-1034.39
Ubuntu 24.04 LTSlinux-azure-6.11pkg:deb/ubuntu/linux-azure-6.11?arch=source&distro=nobleOther threatsAffected
  • <6.11.0-1015.15~24.04.1
Fixed in
  • 6.11.0-1015.15~24.04.1
Ubuntu 24.04 LTSlinux-azure-nvidiapkg:deb/ubuntu/linux-azure-nvidia?arch=source&distro=nobleOther threatsAffected
  • <6.8.0-1022.23
Fixed in
  • 6.8.0-1022.23
Ubuntu 24.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=nobleOther threatsAffected
  • <6.8.0-1036.38
Fixed in
  • 6.8.0-1036.38

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A patch is available and should be applied. The vulnerability is fixed in Linux kernel versions 5.15.0-1088.95~20.04.1 and later as listed in the fixedVersions. Users should update to these fixed kernel versions or later to mitigate the issue. No additional mitigation steps are indicated by the vendor advisory.

Description

CVE-2025-21853 is a vulnerability in the Linux kernel's BPF subsystem where the freeze_mutex is held unnecessarily during mmap operations on BPF maps. This improper locking can lead to potential deadlocks. The issue was reported by syzbot and fixed by limiting the mutex hold time to only the writeability checks and updating the write active count accordingly.

References

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