# CVE-2026-107937: Denial of service in Apache CXF

> Remote attackers can cause denial of service via memory exhaustion by bypassing attachment header limits in Apache CXF.

- **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-RF61847, GHSA-7cpr-66jm-x98h

## What is CVE-2026-107937?

CVE-2026-107937 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

In Apache CXF, the parser for multipart/MTOM attachment part headers did not fully enforce the configured attachment-max-header-size (default 300 characters) and attachment-headers-max-count (default 500) limits. The size limit was applied only to each physical line, not to a header value built from continuation lines or to the combined values of a repeated header. The count limit was checked against the number of distinct header names, not the total number of header lines. A remote, unauthenticated attacker could send a multipart request with very large folded or repeated part headers. The server would then allocate memory without bound, causing a denial of service. 
Users are recommended to upgrade to versions 4.2.4 or 4.1.9 or 3.6.13, which fix this issue.

Weakness: CWE-770 (Allocation of Resources Without Limits or Throttling)

## Which versions are affected by CVE-2026-107937?

It affects 1 product.


Products: Apache Cxf.

## How do I fix CVE-2026-107937?

Upgrade to a fixed version.

## Is CVE-2026-107937 being exploited?

There is no known exploitation of CVE-2026-107937 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-2026-107937 and fix it if it is affected.

What it is: CVE-2026-107937 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-2026-107937 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-2026-107937/ (Markdown: https://insights.sbomify.com/CVE-2026-107937/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-107937
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-107937
- OSV: https://osv.dev/vulnerability/CVE-2026-107937

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-107937/
Summaries are generated and may contain mistakes; the official description above is the record.