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

> A remote attacker can cause a denial of service by supplying a specially crafted ISO file to applications using the Libarchive library.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 19 Mar 2026
- **Updated:** 1 Sep 2026
- **Also known as:** AZL-80400, BELL-CVE-2026-4426, DEBIAN-CVE-2026-4426, ECHO-f87d-ff1f-0ccd, GHSA-r3fp-vrpw-pg77, MINI-8q29-rppm-cjp8, UBUNTU-CVE-2026-4426

## What is CVE-2026-4426?

CVE-2026-4426 is a medium-severity denial of service vulnerability in Libarchive Libarchive, published on 19 Mar 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

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.

Weakness: CWE-1335 (Incorrect Bitwise Shift of Integer)

## Which versions are affected by CVE-2026-4426?

It affects 4 products.


Products: Libarchive Libarchive, Redhat Enterprise Linux, Redhat Hardened Images, Redhat Openshift Container Platform.

## How do I fix CVE-2026-4426?

Apply the vendor's patch.

## Is CVE-2026-4426 being exploited?

There is no known exploitation of CVE-2026-4426 in the wild and no public exploit code.

## Other vulnerabilities in Libarchive Libarchive

- [CVE-2024-37407](https://insights.sbomify.com/CVE-2024-37407/): Memory corruption in n/a (critical 9.1)
- [CVE-2016-1541](https://insights.sbomify.com/CVE-2016-1541/): Memory corruption in n/a (high 8.8)
- [CVE-2016-6250](https://insights.sbomify.com/CVE-2016-6250/): Integer overflow in n/a (high 8.6)
- [CVE-2025-5914](https://insights.sbomify.com/CVE-2025-5914/): Libarchive: double free at archive_read_format_rar_seek_data() in archive_read_support_format_rar.c (high 7.8)
- [CVE-2024-48957](https://insights.sbomify.com/CVE-2024-48957/): Memory corruption in n/a (high 7.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-4426 and fix it if it is affected.

What it is: CVE-2026-4426 is a medium-severity denial of service vulnerability in Libarchive Libarchive, published on 19 Mar 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-4426 in the wild and no public exploit code.

Affected product: Libarchive Libarchive. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-4426/ (Markdown: https://insights.sbomify.com/CVE-2026-4426/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-4426
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-4426
- OSV: https://osv.dev/vulnerability/CVE-2026-4426

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-4426/
Summaries are generated and may contain mistakes; the official description above is the record.