CVE-2026-63898: Linux kernel · USB: serial: mct_u232: fix memory corruption with small endpoint
Affects Linux kernelSource GCVE Database
Not known to be exploited · fixed in 5.15.0-1117.124~20.04.1 : update Linux kernel when convenient.
Data as of 26 Oct 2026, 13:47 UTC
Rated by Threat Radar · No CVSS score from NVD or the CNA
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 13% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 5.15.0-1117.124~20.04.1, 5.15.0-1123.132~20.04.1, 5.15.0-1122.131~20.04.1 +65
Exploitation evidence
Disclosed: evidence found.
CVE published 20 Jul 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
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-gkepkg:deb/ubuntu/linux-gke?arch=source&distro=resoluteOther 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 has been released in updated Linux kernel packages. Users should apply the official kernel updates provided by their distribution vendors and reboot their systems to ensure the fix is applied.
Description
A memory corruption vulnerability was identified and fixed in the Linux kernel's USB serial driver (mct_u232). The flaw involved the driver incorrectly handling the maximum transfer size for devices with a 32-byte bulk-out endpoint that only accepts 16-byte packets, potentially causing slab corruption if a malicious device reports a smaller max packet size. Official patches have been released to address this issue, and users are advised to apply these updates and reboot their systems.
References
- nvd.nist.gov/vuln/detail/CVE-2026-63898 (opens in a new tab)
- git.kernel.org/stable/c/39e295a91e80f3b91f61c7ada2bde434dcaba20d (opens in a new tab)
- git.kernel.org/stable/c/57f332af1745014cd7e40414814ffaa6bc7d3b5b (opens in a new tab)
- git.kernel.org/stable/c/6cb48f8890f9b2051d7c34823057296a536a31c5 (opens in a new tab)
- git.kernel.org/stable/c/90dbad14b109e5fdfb4934ff61e561d11ba3742d (opens in a new tab)
- git.kernel.org/stable/c/915b36d701950503c4ea0f6e314b10868e59fce3 (opens in a new tab)
- git.kernel.org/stable/c/94edbbc5fe00d03cfe1d4e690d7d2cd36317a935 (opens in a new tab)
- git.kernel.org/stable/c/bd2ddb3fe9052ad8703593bbec26ecc7ca92869e (opens in a new tab)
- git.kernel.org/stable/c/d8fdf33d6fcfb90cbec26299baf2352c84b2d768 (opens in a new tab)
- ubuntu.com/security/CVE-2026-63898 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-63898 (opens in a new tab)
- git.kernel.org/linus/915b36d701950503c4ea0f6e314b10868e59fce3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8593-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8603-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8618-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8663-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8664-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8728-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8728-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8728-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8878-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8879-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8877-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8875-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8903-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8905-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8906-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8904-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8903-2 (opens in a new tab)