CVE-2026-23238: Linux kernel · romfs: check sb_set_blocksize() return value
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 5.5 Medium · fixed in 6.8.0-1060.63~22.04.1 : update Linux kernel when convenient.
Data as of 26 Oct 2026, 14:05 UTC
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 9% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 6.8.0-1060.63~22.04.1, 6.8.0-1063.69~22.04.1, 6.8.0-1060.61~22.04.1 +24
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 4 Mar 2026
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.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 25.10linuxpkg:deb/ubuntu/linux@6.17.0-40.40?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-awspkg:deb/ubuntu/linux-aws@6.17.0-1019.19?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-azurepkg:deb/ubuntu/linux-azure@6.17.0-1020.20?arch=source&distro=questingOther threats | 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 25.10linux-gcppkg:deb/ubuntu/linux-gcp@6.17.0-1020.22?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-oraclepkg:deb/ubuntu/linux-oracle@6.17.0-1018.18?arch=source&distro=questingOther 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 should be applied to affected Linux kernel versions. The fix ensures the mount fails if sb_set_blocksize() returns an error, preventing the kernel BUG. Users should update to the fixed kernel versions as per the vendor advisory. No additional mitigation is required beyond applying the official fix.
Description
A vulnerability in the Linux kernel's romfs filesystem code occurs because the return value of sb_set_blocksize() is not checked. This can lead to a kernel BUG when mounting a romfs filesystem on a loop device with an incompatible block size configuration. The issue has been fixed by adding a check for the return value and failing the mount if sb_set_blocksize() fails.
References
- ubuntu.com/security/CVE-2026-23238 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-23238 (opens in a new tab)
- git.kernel.org/linus/ab7ad7abb3660c58ffffdf07ff3bb976e7e0afa0 (opens in a new tab)
- git.kernel.org/stable/c/2c5829cd8fbbc91568c520b666898f57cdcb8cf6 (opens in a new tab)
- git.kernel.org/stable/c/4b71ad7676564a94ec5f7d18298f51e8ae53db73 (opens in a new tab)
- git.kernel.org/stable/c/9b203b8ddd7359270e8a694d0584743555128e2c (opens in a new tab)
- git.kernel.org/stable/c/a381f0f61b35c8894b0bd0d6acef2d8f9b08b244 (opens in a new tab)
- git.kernel.org/stable/c/ab7ad7abb3660c58ffffdf07ff3bb976e7e0afa0 (opens in a new tab)
- git.kernel.org/stable/c/cbd9931e6456822067725354d83446c5bb813030 (opens in a new tab)
- git.kernel.org/stable/c/f2521ab1f63a8c244f06a080319e5ff9a2e1bd95 (opens in a new tab)
- ubuntu.com/security/notices/USN-8492-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8492-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8497-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8498-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8499-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8492-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8492-4 (opens in a new tab)
- ubuntu.com/security/notices/USN-8492-5 (opens in a new tab)
- ubuntu.com/security/notices/USN-8575-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8576-1 (opens in a new tab)