Integer overflow in Linux kernel - CVE-2026-63893

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Main Vulnerability Database Vulnerabilities #VU138760

Integer overflow in Linux kernel - CVE-2026-63893

Published: July 20, 2026


Vulnerability identifier: #VU138760
CSH Severity: Medium
CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-63893
CWE-ID: CWE-190
Exploitation vector: Remote access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a remote attacker to disclose sensitive information.

The vulnerability exists due to an integer overflow leading to an out-of-bounds read in tb_property_entry_valid() in the thunderbolt property parser when processing a crafted XDomain property block from a peer device. A remote attacker can send crafted property entries with wrapped value and length fields to disclose sensitive information.

For TEXT-typed entries using the "deviceid" or "vendorid" keys, leaked data may be exposed through the per-XDomain sysfs device_name or vendor_name attributes. The disclosed data is NUL-bounded and the attacker controls an offset rather than an absolute address.


Affected software

Linux kernel
Ubuntu
linux-ibm (Ubuntu package)
linux-azure (Ubuntu package)
linux-aws (Ubuntu package)
linux-nvidia (Ubuntu package)
linux-nvidia-bos (Ubuntu package)

How to mitigate CVE-2026-63893

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux-ibm (Ubuntu package) - addressed in versions 7.0.0-1008.8, 7.0.0-1010.10
linux-azure (Ubuntu package) - addressed in versions 7.0.0-1009.9, 7.0.0-1010.10
linux-aws (Ubuntu package) - addressed in versions 7.0.0-1009.9, 7.0.0-1015.15
linux-nvidia (Ubuntu package) - addressed in versions 7.0.0-1016.16, 7.0.0-1016.16~24.04.1
linux-nvidia-bos (Ubuntu package) - update to 7.0.0-2016.16

External References

Related Security Bulletins