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Fencer Vulns
medium 5.5

CVE-2026-42495 json

buffer overruns in libfsimage iso9660 handling

published 2026-07-28 3 mo ago modified 2026-07-28 3 mo ago also EUVD-2026-49773

cvss
5.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 9%
public exploits
0
none known

Summary

[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.

Patch / fix

  • xen Debian 12 4.17.7-0+deb12u1
  • xen Debian 13 4.20.3+127-gc42374a105-0+deb13u1
  • xen Debian 14 4.20.3+127-gc42374a105-1

debian advisories DEBIAN-CVE-2026-42495

  • xen SLE Module for Server Applications 15 SP7, SLE Module for Basesystem 15 SP7 4.20.4_04-150700.3.46.1
  • xen SLES for SAP 15 SP4, SLES 15 SP4-LTSS, SLE Micro 5.4 +3 more 4.16.7_12-150400.4.89.3
  • xen SLES for SAP 15 SP5, SLES 15 SP5-LTSS, SLE Micro 5.5 +2 more 4.17.6_14-150500.3.76.3
  • xen SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 4.12.4_72-3.148.4
  • xen SLES for SAP 15 SP6, SLES 15 SP6-LTSS 4.18.5_20-150600.3.53.3

suse advisories SUSE-SU-2026:4090-1SUSE-SU-2026:3462-1SUSE-SU-2026:3451-1SUSE-SU-2026:3423-1SUSE-SU-2026:3409-1

  • xen Alpine 3.21 4.19.6-r0
  • xen Alpine 3.23, Alpine 3.22 4.20.4-r0
  • xen Alpine 3.24 4.21.2-r0

alpine advisories ALPINE-CVE-2026-42495

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
3 mo ago

Exploit prediction

0.20% chance of exploitation in the next 30 days, higher than 9% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
CNA 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Affected products

  • Xen Xen

Classification

Weakness
  • CWE-191 Integer Underflow (Wrap or Wraparound)

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.