CVE-2025-38621: Linux kernel · md: make rdev_addable usable for rcu mode
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 5.5 Medium.
Data as of 26 Oct 2026, 11:42 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 5% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
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 22 Aug 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
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 25.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde@6.17.0-1017.17?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSlinuxpkg:deb/ubuntu/linux@6.8.0-136.136?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSlinux-awspkg:deb/ubuntu/linux-aws@6.8.0-1060.63?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSlinux-aws-6.14pkg:deb/ubuntu/linux-aws-6.14@6.14.0-1018.18~24.04.1?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure@6.8.0-1062.69?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSlinux-azure-6.11pkg:deb/ubuntu/linux-azure-6.11@6.11.0-1018.18~24.04.1?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
No explicit patch links or vendor advisory details are provided in the input data. Until patched, avoid workloads or configurations that trigger md_start_sync under RCU mode or monitor for kernel panics related to md subsystem. Apply kernel updates from trusted sources once available.
Description
A vulnerability in the Linux kernel's md subsystem was resolved that could cause a kernel panic due to a NULL pointer dereference. The issue involved the function rdev_addable being called in an RCU (Read-Copy-Update) context where the rdev->mddev pointer could be set to NULL before a synchronize_rcu call, leading to a crash. The fix involved using READ_ONCE to safely check the pointer's validity. This vulnerability affects specific Linux kernel versions and has a medium severity rating with an impact on availability.
References
- ubuntu.com/security/CVE-2025-38621 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2025-38621 (opens in a new tab)
- git.kernel.org/linus/13017b427118f4311471ee47df74872372ca8482 (opens in a new tab)
- git.kernel.org/stable/c/13017b427118f4311471ee47df74872372ca8482 (opens in a new tab)
- git.kernel.org/stable/c/b5fbe940862339cdcc34dea7a057ad18d18fa137 (opens in a new tab)
- nvd.nist.gov/vuln/detail/CVE-2025-38621 (opens in a new tab)
- git.kernel.org/stable/c/d713e105a6137d3f54f09d4d9e2273482057ca17 (opens in a new tab)