CVE-2026-63891: Linux kernel · thunderbolt: property: Cap recursion depth in __tb_property_parse_dir()
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, 14:05 UTC
Rated by Threat Radar · No CVSS score from NVD or the CNA
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 19% 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 all affected Linux Azure kernel versions to address this vulnerability. The fix includes adding a recursion depth limit and an option to disable the vulnerable feature if not needed. Operators should apply the official kernel updates provided by their vendor. No additional action is required if the system is already updated.
Description
A vulnerability in the Linux kernel's Thunderbolt driver allowed untrusted peers to trigger an unbounded recursive parsing loop, causing kernel stack exhaustion and potential denial of service. This issue was addressed by adding a recursion depth limit and providing an option to disable the affected feature. The vulnerability affects Linux Azure kernel versions prior to certain 7.0.0 builds and specific 5.15 and 4.x versions. A patch is available and should be applied to mitigate the risk.
References
- nvd.nist.gov/vuln/detail/CVE-2026-63891 (opens in a new tab)
- git.kernel.org/stable/c/0a84ab9271936c11e84e511bb52fc5682f8b6726 (opens in a new tab)
- git.kernel.org/stable/c/2b5f47a710172c962ef42d1b732b04d2ad0dce21 (opens in a new tab)
- git.kernel.org/stable/c/830c8a9b467e7d3a158483d37fa7dc13892b293a (opens in a new tab)
- git.kernel.org/stable/c/928abe19fbf0127003abcb1ea69cabc1c897d0ab (opens in a new tab)
- git.kernel.org/stable/c/95839a67ea56ca35732aad7f711404a3127cfe2d (opens in a new tab)
- git.kernel.org/stable/c/b4621e5ef63405c317a84b711faf3bd75b3c6a94 (opens in a new tab)
- git.kernel.org/stable/c/ed9455ef4bd9babc90f92e526abe3fb68c1a8709 (opens in a new tab)
- git.kernel.org/stable/c/f31c6d220f455b5af63590302b30e1b932d14599 (opens in a new tab)
- ubuntu.com/security/CVE-2026-63891 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-63891 (opens in a new tab)
- git.kernel.org/linus/928abe19fbf0127003abcb1ea69cabc1c897d0ab (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)