Improper input validation in Linux kernel - CVE-2026-63964

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Main Vulnerability Database Vulnerabilities #VU138684

Improper input validation in Linux kernel - CVE-2026-63964

Published: July 20, 2026


Vulnerability identifier: #VU138684
CSH Severity: Low
CVSS v4: 6.7 [CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-63964
CWE-ID: CWE-20
Exploitation vector: Local access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a local privileged user to cause a denial of service.

The vulnerability exists due to improper input validation in the do_flash() function in the ucsi_ccg driver when parsing a crafted firmware image without a ':' record header. A local privileged user can place a crafted firmware file under /lib/firmware and write to the do_flash sysfs attribute to cause a denial of service.

The issue can be triggered by an unsigned firmware blob reaching the flashing logic.


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-2026-63964

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