CVE-2026-63892: Linux kernel · thunderbolt: property: Reject dir_len < 4 to prevent size_t underflow
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 vendor-provided patch is available and should be applied to affected Linux kernel versions to remediate this vulnerability. Users should update to the fixed versions as indicated by the vendor advisory.
Description
A vulnerability in the Linux kernel's thunderbolt property parsing code allows size_t underflow when a property entry length is less than 4. This can lead to out-of-bounds memory reads. The issue affects Linux kernel versions prior to certain 7.0.0 Azure-specific releases and some 5.15 and 4.11 versions. A patch is available to address this flaw.
References
- nvd.nist.gov/vuln/detail/CVE-2026-63892 (opens in a new tab)
- git.kernel.org/stable/c/37abc4504fa19d8f9f1e87792e8a2b8fdb308e40 (opens in a new tab)
- git.kernel.org/stable/c/3bec49ca55e08fb085cc4318f24b1b37eaab28cb (opens in a new tab)
- git.kernel.org/stable/c/542a13890b742099c461d70920e97b14e568f6ec (opens in a new tab)
- git.kernel.org/stable/c/5506c825f14d810f0690b1f4367cb7249ebb387a (opens in a new tab)
- git.kernel.org/stable/c/d548179adcc87e1bc66b17e00352a1f536e76065 (opens in a new tab)
- git.kernel.org/stable/c/de21b59c29e31c5108ddc04210631bbfab81b997 (opens in a new tab)
- git.kernel.org/stable/c/de618299190b418291609e6921557253bd417e25 (opens in a new tab)
- git.kernel.org/stable/c/e2d4d51cf5785815fa4e91e0c019e3eb2506a84c (opens in a new tab)
- ubuntu.com/security/CVE-2026-63892 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-63892 (opens in a new tab)
- git.kernel.org/linus/de21b59c29e31c5108ddc04210631bbfab81b997 (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)