CVE-2025-39985: Linux kernel · can: mcba_usb: populate ndo_change_mtu() to prevent buffer overflow
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, 11:20 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 15 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-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)
- ubuntu.com/security/notices/USN-8033-8 (opens in a new tab)
- ubuntu.com/security/notices/USN-8095-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8100-1 (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 patch is available and fixed versions include 5.15.0-1100.107~20.04.2 and later. Users should apply the official Linux kernel updates provided by their distribution, such as the Ubuntu security notice USN-8033-1. After updating, a system reboot is required. The fix populates ndo_change_mtu() to prevent invalid MTU settings and thus blocks the buffer overflow condition.
Description
A buffer overflow vulnerability exists in the Linux kernel's mcba_usb CAN driver due to the lack of proper MTU validation. An attacker can set an invalid MTU and inject malicious CAN XL frames via a PF_PACKET socket, causing the driver to misinterpret frame data and overflow a buffer. This flaw has been fixed by populating the ndo_change_mtu() function to enforce valid MTU limits.
References
- ubuntu.com/security/CVE-2025-39985 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2025-39985 (opens in a new tab)
- git.kernel.org/linus/17c8d794527f01def0d1c8b7dc2d7b8d34fed0e6 (opens in a new tab)
- git.kernel.org/stable/c/0fa9303c4b9493727e0d3a6ac3729300e3013930 (opens in a new tab)
- git.kernel.org/stable/c/17c8d794527f01def0d1c8b7dc2d7b8d34fed0e6 (opens in a new tab)
- git.kernel.org/stable/c/3664ae91b26d1fd7e4cee9cde17301361f4c89d5 (opens in a new tab)
- git.kernel.org/stable/c/37aed407496bf6de8910e588edb04d2435fa7011 (opens in a new tab)
- git.kernel.org/stable/c/6b9fb82df8868dbe9ffea5874b8d35f951faedbb (opens in a new tab)
- git.kernel.org/stable/c/6eec67bfb25637f9b51e584cf59ddace59925bc8 (opens in a new tab)
- git.kernel.org/stable/c/b638c3fb0f163e69785ceddb3b434a9437878bec (opens in a new tab)
- git.kernel.org/stable/c/ca4e51359608e1f29bf1f2c33c3ddf775b6b7ed1 (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)