CVE-2026-63815: Linux kernel · f2fs: bound i_inline_xattr_size for non-inline-xattr inodes
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 8.4 High · fixed in 5.15.0-1117.124~20.04.1 : patch Linux kernel soon.
Data as of 26 Oct 2026, 13:47 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 3% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 5.15.0-1117.124~20.04.1, 5.15.0-1123.132~20.04.1, 5.15.0-1122.131~20.04.1 +44
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 19 Jul 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 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 patch is available and should be applied to affected Linux kernel versions. The fix validates the i_inline_xattr_size field against defined bounds whenever the flexible_inline_xattr feature is enabled, preventing out-of-bounds reads and inode geometry corruption. Users should update to the fixed kernel versions as per vendor advisories such as Ubuntu Security Notice USN-8726-1. No additional mitigation steps are required beyond applying the official fix.
Description
A vulnerability in the Linux kernel's f2fs filesystem affects the handling of the i_inline_xattr_size field for non-inline-xattr inodes when the flexible_inline_xattr feature is enabled. This flaw allows a crafted filesystem image to cause an out-of-bounds read and potential inode geometry corruption by using an attacker-controlled i_inline_xattr_size value. The issue arises because the size is loaded unconditionally but only range-checked under certain conditions, leading to negative values that cause unsafe memory accesses during directory reads. This vulnerability has been resolved by validating i_inline_xattr_size against defined bounds whenever the feature is enabled.
References
- nvd.nist.gov/vuln/detail/CVE-2026-63815 (opens in a new tab)
- git.kernel.org/stable/c/16bc237ce3c483b75575abea53cfb639745311ed (opens in a new tab)
- git.kernel.org/stable/c/2a9f9791653ba5ed3fb45bbffa8d63a7cd5cf706 (opens in a new tab)
- git.kernel.org/stable/c/378acf3cf19b6af6cba55e8dd1154c4e1504bae8 (opens in a new tab)
- git.kernel.org/stable/c/4ce2d52f680c1d8bfdad7cce05b815ea7ca9790d (opens in a new tab)
- ubuntu.com/security/CVE-2026-63815 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-63815 (opens in a new tab)
- git.kernel.org/linus/378acf3cf19b6af6cba55e8dd1154c4e1504bae8 (opens in a new tab)
- ubuntu.com/security/notices/USN-8726-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8727-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8728-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8760-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8781-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8726-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8726-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8800-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8760-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8728-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8726-4 (opens in a new tab)
- ubuntu.com/security/notices/USN-8728-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8876-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8878-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8879-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8877-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8875-1 (opens in a new tab)