CVE-2026-42495 buffer overruns in libfsimage iso9660 handling
An integer underflow in Xen's libfsimage iso9660 driver allows attackers to cause buffer overruns, potentially leading to denial of service or code execution.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-42495?
CVE-2026-42495 is a medium-severity vulnerability in Xen, published on 28 Jul 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
[This CNA information record relates to multiple CVEs; the text explains which aspects/vulnerabilities correspond to which CVE.]
The directory and Rock Ridge / SUSP walk in libfsimage's iso9660 driver derives several lengths directly from attacker-controlled on-disk fields without validating them:
* The directory loop itself assumes a good record length. This is CVE-2026-42494.
* The calculation of the System Use area may underflow. This is CVE-2026-42495.
* The Rock Ridge extension loop assumes a good (inner) record length. This is CVE-2026-62423.
* The Rock Ridge NM record processing assumes a good entry length. This is CVE-2026-62424.
* The Rock Ridge CE record processing assumes a good size and offset. This is CVE-2026-62425.
Weakness: CWE-191
Which versions are affected by CVE-2026-42495?
How do I fix CVE-2026-42495?
Apply the vendor's patch.
Is CVE-2026-42495 being exploited?
There is no known exploitation of CVE-2026-42495 in the wild and no public exploit code.
Sources
Also known as ALPINE-CVE-2026-42495, DEBIAN-CVE-2026-42495, GHSA-5rvw-g8r8-hfmx, UBUNTU-CVE-2026-42495.