CVE-2025-21781: Linux kernel · batman-adv: fix panic during interface removal
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 30 Oct 2026, 23:13 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 +83
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 27 Feb 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: 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 30 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-7521-1 (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)
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 addressing this vulnerability is available and included in multiple updated Linux kernel versions (e.g., 5.4.0-1146.156~18.04.1 and later). Users should apply the official kernel updates provided by their distribution and reboot the system to ensure the fix is active. No additional mitigation steps are required beyond applying the official fix.
Description
CVE-2025-21781 is a vulnerability in the Linux kernel's batman-adv mesh networking protocol that could cause a kernel panic during interface removal. The issue arises because reference counting does not guarantee that the hard interface remains associated with the soft interface until certain work completes, leading to a crash. This flaw was fixed by ensuring proper reference management to prevent premature freeing of objects during work execution. The vulnerability affects specific Linux kernel versions prior to fixed releases in the 5.4.x and 4.11.x series. The CVSS score is 5.5 (medium severity) with impact limited to availability (kernel panic). A patch is available and included in multiple updated kernel versions. Users should apply the official updates and reboot to mitigate the issue.
References
- ubuntu.com/security/CVE-2025-21781 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2025-21781 (opens in a new tab)
- git.kernel.org/linus/ccb7276a6d26d6f8416e315b43b45e15ee7f29e2 (opens in a new tab)
- git.kernel.org/stable/c/072b2787321903287a126c148e8db87dd7ef96fe (opens in a new tab)
- git.kernel.org/stable/c/2c3fb7df4cc6d043f70d4a8a10f8b915bbfb75e7 (opens in a new tab)
- git.kernel.org/stable/c/522b1596ea19e327853804da2de60aeb9c5d6f42 (opens in a new tab)
- git.kernel.org/stable/c/7eb5dd201695645af071592a50026eb780081a72 (opens in a new tab)
- git.kernel.org/stable/c/ccb7276a6d26d6f8416e315b43b45e15ee7f29e2 (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)
- ubuntu.com/security/notices/USN-7521-1 (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)