CVE-2026-63899: Linux kernel · USB: serial: mxuport: 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 should be applied to affected linux-aws kernel versions to resolve this vulnerability. Users should update to linux-aws kernel versions 7.0.0-28.28~24.04.1 or later, or equivalent patched versions. No additional mitigation steps are indicated by the vendor advisory.
Description
A memory corruption vulnerability in the Linux kernel's USB serial mxuport driver has been fixed. The issue arises when a malicious USB device reports a bulk-out endpoint max packet size smaller than eight bytes, which can lead to user-controlled slab corruption. This affects multiple linux-aws kernel versions prior to 7.0.0-28.28~24.04.1 and similar versions. A patch is available and should be applied to mitigate the issue.
References
- nvd.nist.gov/vuln/detail/CVE-2026-63899 (opens in a new tab)
- git.kernel.org/stable/c/086b858b5f5125bc9d967ea2bd825f83d9f8f29d (opens in a new tab)
- git.kernel.org/stable/c/2f3661eb2446e1ef593da45e01a3b21a906768ec (opens in a new tab)
- git.kernel.org/stable/c/4085f0dbb1ce2251c9a5938d693de6593f0ab2bd (opens in a new tab)
- git.kernel.org/stable/c/6c0cf56f00f280d72180bb6ce79741bc787a6269 (opens in a new tab)
- git.kernel.org/stable/c/b40166b4ef96067620a0f248e74ad9658c8f680c (opens in a new tab)
- git.kernel.org/stable/c/be3a1ed4ae51fa8dde57383277d336ce834f2cd9 (opens in a new tab)
- git.kernel.org/stable/c/ccbec56f2f9af008f1574335cc6a668f16603e47 (opens in a new tab)
- git.kernel.org/stable/c/e906545641d34fb1a09a65b4b5cfdff40eb09681 (opens in a new tab)
- ubuntu.com/security/CVE-2026-63899 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-63899 (opens in a new tab)
- git.kernel.org/linus/4085f0dbb1ce2251c9a5938d693de6593f0ab2bd (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)