CVE-2025-21904: Linux kernel · caif_virtio: fix wrong pointer check in cfv_probe()
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 5.5 Medium · fixed in 5.4.0-1146.156~18.04.1 : update Linux kernel when convenient.
Data as of 28 Oct 2026, 12:58 UTC
- Patch
- Available – fixed in 5.4.0-1146.156~18.04.1, 5.4.0-1151.158~18.04.1, 5.4.0-1149.158~18.04.1 +88
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 1 Apr 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Patches and advisories
- ubuntu.com/security/notices/USN-7510-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7510-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7511-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7511-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7512-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7516-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7516-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7517-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7518-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7510-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-7510-4 (opens in a new tab)
- ubuntu.com/security/notices/USN-7510-5 (opens in a new tab)
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 24.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-azure-6.11pkg:deb/ubuntu/linux-azure-6.11?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-azure-nvidiapkg:deb/ubuntu/linux-azure-nvidia?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
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 included in multiple updated Linux kernel versions such as 5.4.0-1146.156~18.04.1 and later. Users should apply the official kernel updates from their Linux distribution vendors and reboot systems to ensure the fix is applied. No additional mitigation steps are required beyond applying the official patches.
Description
A vulnerability in the Linux kernel's caif_virtio driver was fixed by correcting an incorrect pointer check in the cfv_probe() function. The flaw involved checking the wrong pointer before freeing virtqueues, which could lead to improper resource handling. This issue affects multiple Linux kernel versions prior to the fixed releases. The vulnerability has a medium severity score and does not impact confidentiality or integrity but affects availability. A patch is available and included in several updated Linux kernel versions.
References
- ubuntu.com/security/CVE-2025-21904 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2025-21904 (opens in a new tab)
- git.kernel.org/linus/a466fd7e9fafd975949e5945e2f70c33a94b1a70 (opens in a new tab)
- git.kernel.org/stable/c/29e0cd296c87240278e2f7ea4cf3f496b60c03af (opens in a new tab)
- git.kernel.org/stable/c/56cddf71cce3b15b078e937fadab29962b6f6643 (opens in a new tab)
- git.kernel.org/stable/c/597c27e5f04cb50e56cc9aeda75d3e42b6b89c3e (opens in a new tab)
- git.kernel.org/stable/c/7b5fe58959822e6cfa884327cabba6be3b01883d (opens in a new tab)
- git.kernel.org/stable/c/8e4e08ca4cc634b337bb74bc9a70758fdeda0bcb (opens in a new tab)
- git.kernel.org/stable/c/90d302619ee7ce5ed0c69c29c290bdccfde66418 (opens in a new tab)
- git.kernel.org/stable/c/990fff6980d0c1693d60a812f58dbf93eab0473f (opens in a new tab)
- git.kernel.org/stable/c/a466fd7e9fafd975949e5945e2f70c33a94b1a70 (opens in a new tab)
- ubuntu.com/security/notices/USN-7510-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7510-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7511-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7511-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7512-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7516-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7516-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7517-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7518-1 (opens in a new tab)