CVE-2026-43304: Linux kernel · libceph: define and enforce CEPH_MAX_KEY_LEN
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 9.8 Critical · fixed in 5.15.0-1111.118~20.04.1 : patch Linux kernel as a priority.
Data as of 26 Oct 2026, 12:55 UTC
- EPSS
- 0.6% chance of exploitation in 30 days – higher than 49% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 5.15.0-1111.118~20.04.1, 5.15.0-1116.125~20.04.1, 5.15.0-1111.121~20.04.1 +69
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 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@6.17.0-40.40?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-awspkg:deb/ubuntu/linux-aws@6.17.0-1019.19?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-azurepkg:deb/ubuntu/linux-azure@6.17.0-1020.20?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde@6.17.0-1017.17?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-gcppkg:deb/ubuntu/linux-gcp@6.17.0-1020.22?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 has been released by Ubuntu as part of their Linux kernel security updates (USN-8490-1). Users should update to the fixed kernel versions and reboot their systems to apply the changes. Due to an ABI change, recompilation and reinstallation of third-party kernel modules may be required. Follow the vendor advisory instructions for updating to the specified package versions to fully remediate this vulnerability.
Description
A critical vulnerability in the Linux kernel's Ceph Core library was resolved by enforcing a maximum key length (CEPH_MAX_KEY_LEN) during key decoding. The fix ensures that the key material fits into a fixed-size buffer, preventing invalid key lengths that could lead to security issues. This vulnerability affects multiple specific Linux kernel versions and has a high CVSS score of 9.8, indicating severe impact. The issue has been addressed in updated kernel packages, and users are advised to apply these updates and reboot their systems.
References
- ubuntu.com/security/CVE-2026-43304 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-43304 (opens in a new tab)
- git.kernel.org/linus/ac431d597a9bdfc2ba6b314813f29a6ef2b4a3bf (opens in a new tab)
- git.kernel.org/stable/c/1b275bd49e58752efb83767a5d1aed41356c5e64 (opens in a new tab)
- git.kernel.org/stable/c/6405e8c680974bb74e2c98d5249fb52c7b12a6c6 (opens in a new tab)
- git.kernel.org/stable/c/8d745d38c88ecbed95f6b2b39857bf89f35a3244 (opens in a new tab)
- git.kernel.org/stable/c/ac431d597a9bdfc2ba6b314813f29a6ef2b4a3bf (opens in a new tab)
- git.kernel.org/stable/c/c1a0f5f1e5e7e98c36a362ec3d1fcfd9932931ed (opens in a new tab)
- git.kernel.org/stable/c/d82467c07b03a27c3c5469b62bb3b726305a80bb (opens in a new tab)
- git.kernel.org/stable/c/e1dc45d97975f9db65694d234fbddf1915176e16 (opens in a new tab)
- ubuntu.com/security/notices/USN-8490-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8491-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8492-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8493-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8492-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8497-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8498-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8499-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8493-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8508-1 (opens in a new tab)