# CVE-2025-49794: Libxml: heap use after free (uaf) leads to denial of service (dos)

> A use-after-free flaw in libxml2 allows attackers to cause a denial of service via crafted XML documents with specific schematron elements.

- **Severity:** Critical 9.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 16 Jun 2025
- **Updated:** 29 Oct 2026
- **Also known as:** ALPINE-CVE-2025-49794, AZL-64095, AZL-64127, BELL-CVE-2025-49794, DEBIAN-CVE-2025-49794, ECHO-87d5-bef1-89b5, GHSA-qg4c-8pj4-qgw2, UBUNTU-CVE-2025-49794

## What is CVE-2025-49794?

CVE-2025-49794 is a critical use after free vulnerability in Red Hat OpenShift File Integrity Operator - FIO 1, published on 16 Jun 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A use-after-free vulnerability was found in libxml2. This issue occurs when parsing XPath elements under certain circumstances when the XML schematron has the <sch:name path="..."/> schema elements. This flaw allows a malicious actor to craft a malicious XML document used as input for libxml, resulting in the program's crash using libxml or other possible undefined behaviors.

Weakness: CWE-825 (Expired Pointer Dereference)

## Which versions are affected by CVE-2025-49794?


## How do I fix CVE-2025-49794?

Apply the vendor's patch.

## Is CVE-2025-49794 being exploited?

There is no known exploitation of CVE-2025-49794 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-49794 and fix it if it is affected.

What it is: CVE-2025-49794 is a critical use after free vulnerability in Red Hat OpenShift File Integrity Operator - FIO 1, published on 16 Jun 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2025-49794 in the wild and no public exploit code.

Affected product: Red Hat OpenShift File Integrity Operator - FIO 1. 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-2025-49794/ (Markdown: https://insights.sbomify.com/CVE-2025-49794/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-49794
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-49794
- OSV: https://osv.dev/vulnerability/CVE-2025-49794

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From sbomify Insights: https://insights.sbomify.com/CVE-2025-49794/
Summaries are generated and may contain mistakes; the official description above is the record.