Out-of-bounds read in Xen - CVE-2026-31786
Published: April 28, 2026
Vulnerability identifier: #VU128377
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-31786
CWE-ID: CWE-125
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vendor: Xen Project
Affected software:
Xen
Xen
Detailed vulnerability description
The vulnerability allows a local user to disclose sensitive information, cause a denial of service, or escalate privileges.
The vulnerability exists due to an out-of-bounds read in the Xen-related sysfs buildid handler when reading the /sys/hypervisor/properties/buildid sysfs file. A local user can read the crafted sysfs output to disclose sensitive information, cause a denial of service, or escalate privileges.
In rare cases, the issue may also result in writing past the 4 kB sysfs buffer if no zero byte is found in adjacent data.
How to mitigate CVE-2026-31786
Install security update from vendor's website.