CVE-2026-43405: Linux kernel · libceph: Use u32 for non-negative values in ceph_monmap_decode()
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 7.5 High · patch available : patch Linux kernel soon.
Data as of 26 Oct 2026, 12:55 UTC
- EPSS
- 0.5% chance of exploitation in 30 days – higher than 48% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available
CVSS:3.1/AV:N/AC:L/PR:N/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
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 should be applied to affected Linux kernel versions to correct the variable types in libceph and prevent improper memory allocation attempts. Users should update their Linux kernel to a fixed version as per vendor advisories. No additional mitigation is required beyond applying the official fix.
Description
A vulnerability in the Linux kernel's libceph component was fixed by changing certain variables from signed int to unsigned 32-bit integers (u32) in the ceph_monmap_decode() function. The issue involved improper handling of non-negative values, leading to incorrect interpretation of large values as negative, which caused an unnecessary large memory allocation attempt and an incorrect error return. This flaw could result in denial of service due to failed memory allocation. The vulnerability has a CVSS score of 7.5 and affects specific Linux kernel versions. A patch is available to address this issue.
References
- ubuntu.com/security/CVE-2026-43405 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-43405 (opens in a new tab)
- git.kernel.org/linus/770444611f047dbfd4517ec0bc1b179d40c2f346 (opens in a new tab)
- git.kernel.org/stable/c/08bc6173fd611ad5a40f472bf5f15b92aea0fe40 (opens in a new tab)
- git.kernel.org/stable/c/5f2806684b05bd24d05c091083b8e2517ba8ffac (opens in a new tab)
- git.kernel.org/stable/c/770444611f047dbfd4517ec0bc1b179d40c2f346 (opens in a new tab)
- git.kernel.org/stable/c/86f7060cd638d6eb042e8ed780fb83a59ca0dcb3 (opens in a new tab)
- git.kernel.org/stable/c/b268984ae88cb0dcd7a8e8263962c748448e26e8 (opens in a new tab)
- git.kernel.org/stable/c/ba0a4df8c563536857dcbf7b4dbd0f2a15f57ace (opens in a new tab)
- git.kernel.org/stable/c/ee5588e2bc41acb73f6676c0520420c107cd0140 (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-8575-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8576-1 (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-8575-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8576-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8597-1 (opens in a new tab)