CVE-2026-23181: Linux kernel · btrfs: sync read disk super and set block size
Affects Linux kernelSource GCVE Database
Not known to be exploited.
Data as of 26 Oct 2026, 17:16 UTC
Rated by Threat Radar · No CVSS score from NVD or the CNA
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 7% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Exploitation evidence
Disclosed: evidence found.
CVE published 14 Feb 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
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 25.10linuxpkg:deb/ubuntu/linux?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-oraclepkg:deb/ubuntu/linux-oracle?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 fix for this vulnerability has been implemented in the Linux kernel. Users should apply the official kernel updates that resolve the block size synchronization issue during Btrfs mount operations. Patch status is not explicitly confirmed in the provided data; therefore, users should consult the vendor or distribution advisory for the appropriate fixed kernel versions and apply updates accordingly.
Description
A vulnerability in the Linux kernel's Btrfs filesystem handling was resolved involving incorrect block size settings during mount operations. When the block size is changed via the BLKBSZSET command, inconsistent mapping flags cause a mismatch in folio allocation order, leading to assertion failures and potential null pointer dereferences. This occurs because synchronization between the block size change and cache page reads is not properly established, causing memory allocation errors. The issue was reported by syzbot and affects specific Linux kernel versions.
References
- ubuntu.com/security/CVE-2026-23181 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-23181 (opens in a new tab)
- git.kernel.org/linus/3f29d661e5686f3aa14e6f11537ff5c49846f2e2 (opens in a new tab)
- git.kernel.org/stable/c/3f29d661e5686f3aa14e6f11537ff5c49846f2e2 (opens in a new tab)
- git.kernel.org/stable/c/ccb3c75d57039adb3170ae54a0d470e359705984 (opens in a new tab)