CVE-2025-38040: Linux kernel · serial: mctrl_gpio: split disable_ms into sync and no_sync APIs
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 5.5 Medium · fixed in 6.8.0-1046.49~22.04.1 : update Linux kernel when convenient.
Data as of 26 Oct 2026, 16:39 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 9% 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 +33
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 18 Jun 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-aws-6.14pkg:deb/ubuntu/linux-aws-6.14?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– |
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. The fix splits the disable_ms function into synchronous and non-synchronous variants, and callers are updated to use the appropriate API based on locking context. Users should update their Linux kernel to a version including this fix. No additional mitigation is required beyond applying the official kernel update.
Description
A vulnerability in the Linux kernel's serial subsystem involving the mctrl_gpio driver was resolved by splitting the disable_ms function into synchronous and non-synchronous APIs. The issue caused a kernel warning due to a sleeping function being called from an atomic context, which could lead to system instability or crashes. This was observed on platforms using the atmel_serial driver. The fix involves using the appropriate API variant depending on the locking context to avoid invalid sleep calls.
References
- ubuntu.com/security/CVE-2025-38040 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2025-38040 (opens in a new tab)
- git.kernel.org/linus/1bd2aad57da95f7f2d2bb52f7ad15c0f4993a685 (opens in a new tab)
- git.kernel.org/stable/c/1bd2aad57da95f7f2d2bb52f7ad15c0f4993a685 (opens in a new tab)
- git.kernel.org/stable/c/68435c1fa3db696db4f480385db9e50e26691d0d (opens in a new tab)
- git.kernel.org/stable/c/7187ec6b0b9ff22ebac2c3bb4178b7dbbdc0a55a (opens in a new tab)
- git.kernel.org/stable/c/c504c11b94d6e4ad818ca5578dffa8ff29ad0f20 (opens in a new tab)
- git.kernel.org/stable/c/e6a46719a2369eb5186d4f7e6c0478720ca1ec3d (opens in a new tab)
- ubuntu.com/security/notices/USN-7769-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7770-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7771-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7769-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7769-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-7789-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7789-2 (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)