CVE-2026-4426 | Libarchive: libarchive: denial of service via malformed iso file processing

A flaw was found in libarchive. An Undefined Behavior vulnerability exists in the zisofs decompression logic, caused by improper validation of a field (`pz_log2_bs`) read from ISO9660 Rock Ridge extensions. A remote attacker can exploit this by supplying a specially crafted ISO file. This can lead to incorrect memory allocation and potential application crashes, resulting in a denial-of-service (DoS) condition.

Published: 2026-03-19 Last update: 2026-05-03 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-4426 is rated Low Risk (33.8/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.30%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-4426

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.19% 0.30% +0.11%
2 2026-05-06 0.11% 0.19% +0.08%
3 2026-03-20 — 0.11% —

Full EPSS history (3 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-4426

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.5 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.8 3.6 [email protected]

Weakness enumeration for CVE-2026-4426

GitHub Security Advisory for CVE-2026-4426

GHSA-r3fp-vrpw-pg77 · Severity: medium — A flaw was found in libarchive. An Undefined Behavior vulnerability exists in the zisofs...

OS Trackers for CVE-2026-4426

vendor priority summary link
debian not yet assigned CVE-2026-4426 not yet assigned priority: Debian including 1 source packages (libarchive), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2026-4426
redhat medium — https://access.redhat.com/security/cve/CVE-2026-4426
suse high — https://www.suse.com/security/cve/CVE-2026-4426/
ubuntu medium CVE-2026-4426 medium priority: Ubuntu including 1 source packages (libarchive), 8 status rows across 8 suites (bionic, focal, jammy, noble, questing, trusty, upstream, xenial): deferred 7, needs-triage 1. https://ubuntu.com/security/CVE-2026-4426

Affected software / configurations for CVE-2026-4426

Vendor Product Version Raw CPE
libarchive libarchive — cpe:2.3:a:libarchive:libarchive:-:*:*:*:*:*:*:*
redhat hardened_images — cpe:2.3:a:redhat:hardened_images:-:*:*:*:*:*:*:*
redhat openshift_container_platform 4.0 cpe:2.3:a:redhat:openshift_container_platform:4.0:*:*:*:*:*:*:*
redhat enterprise_linux 6.0 cpe:2.3:o:redhat:enterprise_linux:6.0:*:*:*:*:*:*:*
redhat enterprise_linux 7.0 cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:*
redhat enterprise_linux 8.0 cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*
redhat enterprise_linux 9.0 cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:*
redhat enterprise_linux 10.0 cpe:2.3:o:redhat:enterprise_linux:10.0:*:*:*:*:*:*:*

References for CVE-2026-4426

cvelogic Threat Intelligence