CVE-2026-31396: Linux kernel · net: macb: fix use-after-free access to PTP clock
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 7.8 High · patch available : patch Linux kernel soon.
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
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 3 Apr 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 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– |
Ubuntu 25.10linux-oraclepkg:deb/ubuntu/linux-oracle@6.17.0-1018.18?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
An official patch is available and should be applied to affected linux-azure kernel versions. Users should update to the fixed kernel versions provided by their vendor. No additional mitigation steps are indicated beyond applying the official fix.
Description
A use-after-free vulnerability in the Linux kernel's macb network driver related to PTP clock handling has been resolved. The issue occurs because the PTP clock is registered on every interface opening and destroyed on every closing, but can still be accessed via ethtool calls while the interface is present in the kernel. This leads to a use-after-free condition causing potential kernel memory corruption. The vulnerability affects specific linux-azure kernel versions and has a CVSS score of 7.8. A patch is available to fix this issue.
References
- ubuntu.com/security/CVE-2026-31396 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-31396 (opens in a new tab)
- git.kernel.org/linus/8da13e6d63c1a97f7302d342c89c4a56a55c7015 (opens in a new tab)
- git.kernel.org/stable/c/0bb848d8c64938024e45780f8032f1f67d3a3607 (opens in a new tab)
- git.kernel.org/stable/c/1f4714065b2bcbb0a4013fd355b84b848e6cc345 (opens in a new tab)
- git.kernel.org/stable/c/341d01087f821aa0f165fb1ffc8bfe4e50776da7 (opens in a new tab)
- git.kernel.org/stable/c/5653af416a48f6c18f9626ae9df96f814f45ff34 (opens in a new tab)
- git.kernel.org/stable/c/8da13e6d63c1a97f7302d342c89c4a56a55c7015 (opens in a new tab)
- git.kernel.org/stable/c/eb652535e9ec795ef5c1078f7578eaaed755268b (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-8595-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8606-1 (opens in a new tab)