buffer overruns in libfsimage iso9660 handling
Published Jul 28, 2026
5.5
MEDIUMCVSS 3.1
EPSS 0.15%
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.
Affected products
No data.
No data.
No data.
No Red Hat product state for this CVE.
No package ranges for this CVE.
Remediation
Vendor solution
XSA-443 added a mechanism to run pygrub de-privileged. Using this mode will mitigate the vulnerability.
Ensuring that guests do not use the pygrub bootloader will avoid this vulnerability.
For cases where the PV guest is known to be 64bit, and uses grub2 as a bootloader, pvgrub is a suitable alternative to pygrub.
Running only HVM or PVH guests will avoid the vulnerability.
Metrics
No CVSS v4.0 score for this CVE.
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
No CVSS v3.0 score for this CVE.
No CVSS v2.0 score for this CVE.
This CVE is not in the KEV list.
CISA SSVC (Vulnrichment)
Stakeholder-Specific Vulnerability Categorization from CISA ADP.
Exploitation
NoneAutomatable
NoTechnical Impact
PartialDecision
n/aAssessed Jul 28, 2026 · SSVC 2.0.3
Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 3, 2026.
Score over time
Jul–Oct 2026- EPSS v5
Percentile over time
- EPSS v5
Table of values (2 key points)
Flat stretches are collapsed; showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 3, 2026 | 0.15% (0.00148) | 3.43th | v5 (v2026.06.15) |
| Jul 29, 2026 | 0.21% (0.00205) | 10.73th | v5 (v2026.06.15) |
References (1)
Change history (0)
No recorded changes yet.