CVE-2025-37879: Linux kernel · 9p/net: fix improper handling of bogus negative read/write replies
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 9.8 Critical · fixed in 6.8.0-1046.49~22.04.1 : patch Linux kernel as a priority.
Data as of 26 Oct 2026, 16:39 UTC
- EPSS
- 0.7% chance of exploitation in 30 days – higher than 53% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 6.8.0-1046.49~22.04.1, 6.8.0-1051.57~22.04.1, 6.8.0-1046.53~22.04.1 +29
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 9 May 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.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 25.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-azure-6.11pkg:deb/ubuntu/linux-azure-6.11?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=nobleOther 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
An official patch is available and should be applied promptly. The vulnerability is fixed in updated Linux kernel releases as detailed in vendor advisories such as Ubuntu Security Notice USN-7594-1. Users should update their Linux kernel packages to the fixed versions provided by their distribution vendors. No additional mitigation steps are indicated beyond applying the official fix.
Description
A vulnerability in the Linux kernel's 9p/net subsystem was resolved by correcting improper handling of negative read/write replies. The issue involved signed variables incorrectly interpreting negative counts as valid, which could lead to a null pointer dereference. The fix involved making these variables unsigned to prevent this erroneous condition. Multiple Linux kernel versions are affected. A high-severity CVSS 3.1 score of 9.8 indicates critical impact on confidentiality, integrity, and availability. An official patch is available as part of broader Linux kernel security updates.
References
- ubuntu.com/security/CVE-2025-37879 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2025-37879 (opens in a new tab)
- git.kernel.org/linus/d0259a856afca31d699b706ed5e2adf11086c73b (opens in a new tab)
- git.kernel.org/stable/c/374e4cd75617c8c2552f562f39dd989583f5c330 (opens in a new tab)
- git.kernel.org/stable/c/468ff4a7c61fb811c596a7c44b6a5455e40fd12b (opens in a new tab)
- git.kernel.org/stable/c/a68768e280b7d0c967ea509e791bb9b90adc94a5 (opens in a new tab)
- git.kernel.org/stable/c/c548f95688e2b5ae0e2ae43d53cf717156c7d034 (opens in a new tab)
- git.kernel.org/stable/c/d0259a856afca31d699b706ed5e2adf11086c73b (opens in a new tab)
- ubuntu.com/security/notices/USN-7594-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7594-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7594-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8028-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8028-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8031-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8028-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8028-4 (opens in a new tab)
- ubuntu.com/security/notices/USN-8028-5 (opens in a new tab)
- ubuntu.com/security/notices/USN-8031-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8028-6 (opens in a new tab)
- ubuntu.com/security/notices/USN-8031-3 (opens in a new tab)