# CVE-2026-108039: Apache CXF: Prevent unbounded XML document size in StaxUtils by adding default element and character limits

> Attackers can cause denial of service by sending large XML documents to Apache CXF, which previously lacked default parsing limits.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/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:** Not needed
- **Fix available:** Yes
- **Published:** 9 Oct 2026
- **Updated:** 15 Oct 2026
- **Also known as:** CLEANSTART-2026-IW56621, GHSA-v2mw-x6g2-24jf

## What is CVE-2026-108039?

CVE-2026-108039 is a high-severity denial of service vulnerability in Apache Cxf, published on 9 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

By default, StaxUtils placed no limit on the total number of elements or the total number of characters in an XML document. A very large request could therefore use a lot of memory and CPU during parsing, especially where CXF builds a DOM from the input (for example SAAJ or WS-Security), and could cause a denial of service when no request size limit was configured. Both limits now have defaults: the maximum element count is 100 × maxChildElements (5,000,000 by default), and the maximum document size is 256M characters. Applications that process larger documents can raise the limits with the org.apache.cxf.stax.maxElementCount and org.apache.cxf.stax.maxXMLCharacters properties.
Users are recommended to upgrade to versions 4.2.4 or 4.1.9 or 3.6.13, which fix this issue.

Weakness: CWE-776 (Improper Restriction of Recursive Entity References in DTDs)

## Which versions are affected by CVE-2026-108039?

It affects 1 product.


Products: Apache Cxf.

## How do I fix CVE-2026-108039?

Upgrade to a fixed version.

## Is CVE-2026-108039 being exploited?

There is no known exploitation of CVE-2026-108039 in the wild and no public exploit code.

## Other vulnerabilities in Apache Cxf

- [CVE-2012-2379](https://insights.sbomify.com/CVE-2012-2379/): XML Signature/Encryption Not Validated in Apache CXF (critical 10.0)
- [CVE-2026-66909](https://insights.sbomify.com/CVE-2026-66909/): Apache CXF: Unsafe deserialization of inbound JMS ObjectMessage (critical 9.8)
- [CVE-2026-68079](https://insights.sbomify.com/CVE-2026-68079/): Apache CXF: DefaultEncryptingCodeDataProvider allows unlimited authorization code replay (critical 9.8)
- [CVE-2026-50628](https://insights.sbomify.com/CVE-2026-50628/): Apache CXF: OAuth2: Inverted IP Binding Check Defeats Security Control (critical 9.8)
- [CVE-2025-48913](https://insights.sbomify.com/CVE-2025-48913/): Apache CXF: Untrusted JMS configuration can lead to RCE (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-108039 and fix it if it is affected.

What it is: CVE-2026-108039 is a high-severity denial of service vulnerability in Apache Cxf, published on 9 Oct 2026. 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-2026-108039 in the wild and no public exploit code.

Affected product: Apache Cxf. 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-2026-108039/ (Markdown: https://insights.sbomify.com/CVE-2026-108039/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-108039
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-108039
- OSV: https://osv.dev/vulnerability/CVE-2026-108039

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-108039/
Summaries are generated and may contain mistakes; the official description above is the record.