CVE-2025-21694: Linux kernel · fs/proc: fix softlockup in __read_vmcore (part
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 5.5 Medium · fixed in 5.4.0-1142.152~18.04.1 : update Linux kernel when convenient.
Data as of 29 Oct 2026, 22:35 UTC
- Patch
- Available – fixed in 5.4.0-1142.152~18.04.1, 5.4.0-1147.154~18.04.1, 5.4.0-1145.154~18.04.1 +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 12 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 29 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Patches and advisories
- ubuntu.com/security/notices/USN-7387-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7388-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7389-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7390-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7387-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7387-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-7391-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7392-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7393-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7392-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7392-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-7401-1 (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.
Description
In the Linux kernel, the following vulnerability has been resolved: fs/proc: fix softlockup in __read_vmcore (part 2) Since commit 5cbcb62dddf5 ("fs/proc: fix softlockup in __read_vmcore") the number of softlockups in __read_vmcore at kdump time have gone down, but they still happen sometimes. In a memory constrained environment like the kdump image, a softlockup is not just a harmless message, but it can interfere with things like RCU freeing memory, causing the crashdump to get stuck. The second loop in __read_vmcore has a lot more opportunities for natural sleep points, like scheduling out while waiting for a data write to happen, but apparently that is not always enough. Add a cond_resched() to the second loop in __read_vmcore to (hopefully) get rid of the softlockups.
References
- ubuntu.com/security/CVE-2025-21694 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2025-21694 (opens in a new tab)
- git.kernel.org/linus/cbc5dde0a461240046e8a41c43d7c3b76d5db952 (opens in a new tab)
- git.kernel.org/stable/c/649b266606bc413407ce315f710c8ce8a88ee30a (opens in a new tab)
- git.kernel.org/stable/c/65c367bd9d4f43513c7f837df5753bea9561b836 (opens in a new tab)
- git.kernel.org/stable/c/80828540dad0757b6337c6561d49c81038f38d87 (opens in a new tab)
- git.kernel.org/stable/c/80da29deb88a3a907441fc35bb7bac309f31e713 (opens in a new tab)
- git.kernel.org/stable/c/84c4ed15626574c9ac6c1039ba9c137a77bcc7f2 (opens in a new tab)
- git.kernel.org/stable/c/a5a2ee8144c3897d37403a69118c3e3dc5713958 (opens in a new tab)
- git.kernel.org/stable/c/cbc5dde0a461240046e8a41c43d7c3b76d5db952 (opens in a new tab)
- ubuntu.com/security/notices/USN-7387-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7388-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7389-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7390-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7387-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7387-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-7391-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7392-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7393-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7392-2 (opens in a new tab)