CVE-2025-40027: Linux kernel · net/9p: fix double req put in p9_fd_cancelled
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 7.8 High · fixed in 5.15.0-1100.107~20.04.2 : patch Linux kernel soon.
Data as of 28 Oct 2026, 11:19 UTC
- Patch
- Available – fixed in 5.15.0-1100.107~20.04.2, 5.15.0-1110.119~20.04.1, 5.15.0-1100.109~20.04.1 +68
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 28 Oct 2025
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.
Patches and advisories
- ubuntu.com/security/notices/USN-7906-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7906-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7906-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8033-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8033-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8033-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8034-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8033-4 (opens in a new tab)
- ubuntu.com/security/notices/USN-8033-5 (opens in a new tab)
- ubuntu.com/security/notices/USN-8034-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8033-6 (opens in a new tab)
- ubuntu.com/security/notices/USN-8033-7 (opens in a new tab)
Affected software
| Product | 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
|
Ubuntu 25.10linux-oraclepkg:deb/ubuntu/linux-oracle?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 fix is available and has been released in multiple updated Linux kernel versions as listed in the established facts and Ubuntu security notices USN-7906-1 and USN-7906-2. Users should apply these kernel updates and reboot their systems to ensure the vulnerability is remediated. Due to an ABI change, recompilation and reinstallation of third-party kernel modules may be required. No additional mitigation steps are indicated beyond applying the official patches.
Description
CVE-2025-40027 is a concurrency vulnerability in the Linux kernel's 9p filesystem client. It involves a race condition causing a double removal of a request from a list, leading to a potential use-after-free or memory corruption. The flaw was identified by Syzkaller and fixed by updating the status check in the p9_fd_cancelled function to prevent double deletion. This vulnerability affects multiple Linux kernel versions and has been addressed in several patched releases.
References
- ubuntu.com/security/CVE-2025-40027 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2025-40027 (opens in a new tab)
- git.kernel.org/stable/c/0e0097005abc02c9f262370674f855625f4f3fb4 (opens in a new tab)
- git.kernel.org/stable/c/284e67a93b8c48952b6fc82129a8d3eb9dc73b06 (opens in a new tab)
- git.kernel.org/stable/c/448db01a48e1cdbbc31c995716a5dac1e52ba036 (opens in a new tab)
- git.kernel.org/stable/c/674b56aa57f9379854cb6798c3bbcef7e7b51ab7 (opens in a new tab)
- git.kernel.org/stable/c/716dceb19a9f8ff6c9d3aee5a771a93d6a47a0b6 (opens in a new tab)
- git.kernel.org/stable/c/94797b84cb9985022eb9cb3275c9497fbc883bb6 (opens in a new tab)
- git.kernel.org/stable/c/c1db864270eb7fea94a9ef201da0c9dc1cbab7b8 (opens in a new tab)
- ubuntu.com/security/notices/USN-7906-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7906-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7906-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8033-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8033-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8033-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8034-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8033-4 (opens in a new tab)
- ubuntu.com/security/notices/USN-8033-5 (opens in a new tab)
- ubuntu.com/security/notices/USN-8034-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8033-6 (opens in a new tab)