CVE-2026-43338: Linux kernel · btrfs: reserve enough transaction items for qgroup ioctls
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 5.5 Medium · fixed in 6.8.0-1061.64~22.04.1 : update Linux kernel when convenient.
Data as of 26 Oct 2026, 13:47 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 1% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 6.8.0-1061.64~22.04.1, 6.8.0-1063.71~22.04.1, 6.8.0-1062.69~22.04.1 +30
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 8 May 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 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde@7.0.0-1008.8?arch=source&distro=resoluteOther threats | 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– |
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 to resolve this issue. The vendor advisory from Ubuntu confirms that this vulnerability is addressed in updated kernel packages. Users should update their Linux kernel to the fixed versions provided by their distribution. No additional mitigation actions are indicated or required beyond applying the official fix.
Description
A vulnerability in the Linux kernel's Btrfs filesystem related to transaction item reservation for quota group (qgroup) ioctls has been resolved. The issue involved insufficient reservation of space for quota tree updates and delayed references, which could cause transaction aborts due to space exhaustion (-ENOSPC). This was demonstrated by a test script triggering transaction aborts during delayed reference processing. The vulnerability affects specific Linux kernel versions and has a CVSS score of 5.5 with low severity. A patch is available to address this issue.
References
- ubuntu.com/security/CVE-2026-43338 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-43338 (opens in a new tab)
- git.kernel.org/linus/f9a4e3015db1aeafbef407650eb8555445ca943e (opens in a new tab)
- git.kernel.org/stable/c/386f5e16a383101a68e195c806b4eedb233cd1d3 (opens in a new tab)
- git.kernel.org/stable/c/bb6eb33c908edbbb4d92abdc0c6c87f21b4952e8 (opens in a new tab)
- git.kernel.org/stable/c/cf930a651eef6f8d915bf0ccd60c2045974f870c (opens in a new tab)
- git.kernel.org/stable/c/f9a4e3015db1aeafbef407650eb8555445ca943e (opens in a new tab)
- ubuntu.com/security/notices/USN-8567-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8574-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8574-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8595-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8596-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8595-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8606-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8607-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8608-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8609-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8574-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8595-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8619-1 (opens in a new tab)