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NVD / CVE Program· CNA XEN

CVE-2026-42495: buffer overruns in libfsimage iso9660 handling

Noroxi assessment

Priority: Monitor (action score 22/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.19% (FIRST EPSS).
  • Someone with local access to the system can trigger it. No account or password is required. A user must open a link or visit a page. No special conditions are required; it is repeatable.
  • Fixed version: xen (Alpine:v3.21) 4.19.6-r0; xen (Alpine:v3.22) 4.20.4-r0; xen (Alpine:v3.24) 4.21.2-r0.

Low priority for now. Upgrade to xen (Alpine:v3.21) 4.19.6-r0; xen (Alpine:v3.22) 4.20.4-r0; xen (Alpine:v3.24) 4.21.2-r0 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

[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.

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
Jul 28, 2026
Updated
Jul 28, 2026
EPSS
0.1% · 9th percentile

Report tools

JSON

Action score

22

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-42495

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (XEN). Independent of NVD's CPE analysis and usually ahead of it.

  • Xen Xen

    • consult Xen advisory XSA-497unknown

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Alpine:v3.21xenbefore 4.19.6-r04.19.6-r0
Alpine:v3.22xenbefore 4.20.4-r04.20.4-r0
Alpine:v3.24xenbefore 4.21.2-r04.21.2-r0
Debian:12xenbefore 4.17.7-0+deb12u14.17.7-0+deb12u1
Debian:13xenbefore 4.20.3+127-gc42374a105-0+deb13u14.20.3+127-gc42374a105-0+deb13u1
Debian:14xenbefore 4.20.3+127-gc42374a105-14.20.3+127-gc42374a105-1
SUSE:Linux Enterprise Micro 5.3xenbefore 4.16.7_12-150400.4.89.34.16.7_12-150400.4.89.3
SUSE:Linux Enterprise Micro 5.5xenbefore 4.17.6_14-150500.3.76.34.17.6_14-150500.3.76.3
SUSE:Linux Enterprise Module for Basesystem 15 SP7xenbefore 4.20.4_04-150700.3.46.14.20.4_04-150700.3.46.1
SUSE:Linux Enterprise Server 12 SP5-LTSSxenbefore 4.12.4_72-3.148.44.12.4_72-3.148.4
SUSE:Linux Enterprise Server 15 SP6-LTSSxenbefore 4.18.5_20-150600.3.53.34.18.5_20-150600.3.53.3

Same product

xen: all records

Other highest-scoring records for the same primary product.

  • CVE-2017-10921The grant-table feature in Xen through 4.8.x does not ensure sufficient type counts for a GNTMAP_device_map and GNTMAP_host_map mapping, whi
    41Plan
  • CVE-2017-10920The grant-table feature in Xen through 4.8.x mishandles a GNTMAP_device_map and GNTMAP_host_map mapping, when followed by only a GNTMAP_host
    41Plan
  • CVE-2017-10918Xen through 4.8.x does not validate memory allocations during certain P2M operations, which allows guest OS users to obtain privileged host
    41Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-42493Jul 28, 2026 · x86 shadow paging is deprecated
    30Monitor
  • ← EarlierCVE-2026-42494Jul 28, 2026 · buffer overruns in libfsimage iso9660 handling
    24Monitor
  • Later →CVE-2026-62423Jul 28, 2026 · buffer overruns in libfsimage iso9660 handling
    22Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
alpine:xen4.19.6-r0 · Alpine:v3.21Package registry (OSV)
debian:xen4.17.7-0+deb12u1 · Debian:12Package registry (OSV)
debian:xen4.20.3+127-gc42374a105-0+deb13u1 · Debian:13Package registry (OSV)
suse:xen4.18.5_20-150600.3.53.3 · SUSE:Linux Enterprise Server 15 SP6-LTSSPackage registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-10269977 days apartArm: multiple issues with GNTTABOP_cache_flush
    30Monitor
  • CVE-2026-10270277 days apartArm: multiple issues with GNTTABOP_cache_flush
    30Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • No account or password is required.
  • A user must open a link or visit a page.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
None
User interaction
Required
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-191 · Integer Underflow (Wrap or Wraparound)

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records