CVE-2026-98959: Linux kernel · btrfs: fix xattr replace when multiple xattrs are packed in the same item
Affects Linux kernelSource CVE Database V5
Not known to be exploited · CVSS 9.8 Critical · fixed in c1803697a60f22743aa28ad522f805e92d45e3f0 : patch Linux kernel as a priority.
Data as of 26 Oct 2026, 14:18 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.
- Patch
- Available – fixed in c1803697a60f22743aa28ad522f805e92d45e3f0, a97114b9b00ed3d05156f3b2ddbf797296260389, 5877d7138cc4359d26fd7b010eedfd1b3162348f +6
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 23 Oct 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 |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in– |
AI-suggested
This vulnerability has been fixed in Linux kernel versions 3.11, 3.13, 3.15, and 3.19 and corresponding commits. Users should upgrade to these fixed versions or later to remediate the issue. No additional mitigation steps are required once the system is updated.
Description
CVE-2026-98959 is a critical vulnerability in the Linux kernel's Btrfs filesystem related to extended attribute (xattr) handling. When multiple xattrs are packed in the same btrfs_dir_item and one xattr is replaced with a value of a different size, the kernel fails to fully initialize the new btrfs_dir_item. This causes filesystem corruption detected during extent buffer writeback, leading to transaction aborts and potential data loss. The issue occurs because the deletion and insertion of xattr items shift data in the leaf, leaving parts uninitialized. The vulnerability affects multiple Linux kernel versions prior to 3.11, 3.13, 3.15, and 3.19, with fixes applied in those versions. The CVSS 3.1 score is 9.8, indicating critical severity.
References
- git.kernel.org/stable/c/7a53bb4668b319fc6c8a3ce2c21635125c7d2712 (opens in a new tab)
- git.kernel.org/stable/c/5877d7138cc4359d26fd7b010eedfd1b3162348f (opens in a new tab)
- git.kernel.org/stable/c/a97114b9b00ed3d05156f3b2ddbf797296260389 (opens in a new tab)
- git.kernel.org/stable/c/c1803697a60f22743aa28ad522f805e92d45e3f0 (opens in a new tab)
- git.kernel.org/stable/c/858bee1c77857aabcc2327cd32dd8266332de332 (opens in a new tab)