Xen libfsimage iso9660 driver integer overflow

Summaryinfo

A vulnerability identified as critical has been detected in Xen libfsimage. Impacted is an unknown function of the component iso9660 driver. The manipulation leads to integer overflow. This vulnerability is documented as CVE-2026-42495. The attack can be initiated remotely. There is not any exploit available.

Detailsinfo

A vulnerability, which was classified as critical, has been found in Xen libfsimage (affected version not known). This issue affects some unknown functionality of the component iso9660 driver. The manipulation with an unknown input leads to a integer overflow vulnerability. Using CWE to declare the problem leads to CWE-190. The product performs a calculation that can produce an integer overflow or wraparound, when the logic assumes that the resulting value will always be larger than the original value. This can introduce other weaknesses when the calculation is used for resource management or execution control. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

[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.

The advisory is shared at xenbits.xenproject.org. The identification of this vulnerability is CVE-2026-42495 since 04/27/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 08/02/2026).

The vulnerability scanner Nessus provides a plugin with the ID 331597 (Fedora 44 : xen (2026-bf1da84dfc)), which helps to determine the existence of the flaw in a target environment.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the databases at Tenable (331597) and CERT Bund (WID-SEC-2026-2568). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Affected

• Open Source Xen

Productinfo

Type

• Virtualization Software

Vendor

• Xen

Name

• libfsimage

License

• open-source

CPE 2.3info

• 🔒

CPE 2.2info

• 🔒

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Exploitinginfo

Threat Intelligenceinfo

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Entryinfo

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

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