CVE-2026-80734: Linux kernel · btrfs: initialize inode mapping flags for cached inodes
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 8.8 High.
Data as of 26 Oct 2026, 12:55 UTC
- EPSS
- 0.6% chance of exploitation in 30 days – higher than 48% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 3 Sep 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 26.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-gkepkg:deb/ubuntu/linux-gke?arch=source&distro=resoluteOther 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 is available that ensures inode mapping flags and minimal folio order are properly initialized for cached inodes in the Btrfs filesystem. Users should update to a Linux kernel version that includes this patch. No additional mitigations are specified or required beyond applying the official fix.
Description
A vulnerability in the Linux kernel's Btrfs filesystem was resolved that caused a kernel BUG due to improper initialization of inode mapping flags for cached inodes. The issue arises when cached inodes do not have their minimal folio order set correctly, leading to misaligned folio sizes and triggering assertion failures. This bug could cause system crashes during certain file operations involving Btrfs. The fix ensures that the inode mapping flags and minimal folio order are always set correctly, even for cached inodes.
References
- nvd.nist.gov/vuln/detail/CVE-2026-80734 (opens in a new tab)
- git.kernel.org/stable/c/0d26249671171ab759cb4fdce673554a690fa655 (opens in a new tab)
- git.kernel.org/stable/c/0ef349734a93227b45f65fc50a3311d1cc5f03e9 (opens in a new tab)
- ubuntu.com/security/CVE-2026-80734 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-80734 (opens in a new tab)
- git.kernel.org/linus/0ef349734a93227b45f65fc50a3311d1cc5f03e9 (opens in a new tab)
- git.kernel.org/stable/c/e18b8236c57fcc67d793bfc866f4bb2581be9f72 (opens in a new tab)