CVE-2026-42494 Details
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.
A buffer overrun vulnerability has been identified in the iso9660 driver of libfsimage, present in all Xen versions from 3.2 onwards. This vulnerability arises because the directory and Rock Ridge/SUSP processing loops derive lengths from attacker-controlled on-disk fields without proper validation. Specifically, the directory loop assumes a valid record length, leading to potential exploitation.
To address this vulnerability, the attached patch can be applied. For guests known to be 64-bit and using grub2 as a bootloader, pvgrub is a suitable alternative to pygrub. Running only HVM or PVH guests will also avoid the vulnerability.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Jul 28, 2026CISA-ADP
Assessed Jul 28, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://xenbits.xenproject.org/xsa/advisory-497.html | [email protected] | AdvisoryBundleRemedyVendor |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-125 | Out-of-bounds Read | CISA-ADP |
Affected Products
| Product | Versions |
|---|---|
| Xen | >= 3.2 |
CPE
Remediation
| |
Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 28, 2026 | CVE Modified | CISA-ADP |
| Jul 28, 2026 | New CVE Received | [email protected] |