Apache CXF up to 3.6.12/4.1.8/4.2.3 Parser denial of service

Summaryinfo

A vulnerability was found in Apache CXF up to 3.6.12/4.1.8/4.2.3. It has been classified as problematic. Affected by this vulnerability is an unknown functionality of the component Parser. Performing a manipulation results in denial of service. This vulnerability was named CVE-2026-107937. The attack may be initiated remotely. There is no available exploit. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability was found in Apache CXF up to 3.6.12/4.1.8/4.2.3. It has been classified as problematic. This affects an unknown code block of the component Parser. The manipulation with an unknown input leads to a denial of service vulnerability. CWE is classifying the issue as CWE-404. The product does not release or incorrectly releases a resource before it is made available for re-use. This is going to have an impact on availability. The summary by CVE is:

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.

The advisory is shared at lists.apache.org. This vulnerability is uniquely identified as CVE-2026-107937 since 10/09/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 10/09/2026). MITRE ATT&CK project uses the attack technique T1499 for this issue.

Upgrading to version 3.6.13, 4.1.9 or 4.2.4 eliminates this vulnerability.

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Productinfo

Type

• Application Server Software

Vendor

• Apache

Name

• CXF

Version

• 3.6.0
• 3.6.1
• 3.6.2
• 3.6.3
• 3.6.4
• 3.6.5
• 3.6.6
• 3.6.7
• 3.6.8
• 3.6.9
• 3.6.10
• 3.6.11
• 3.6.12
• 4.1.0
• 4.1.1
• 4.1.2
• 4.1.3
• 4.1.4
• 4.1.5
• 4.1.6
• 4.1.7
• 4.1.8
• 4.2.0
• 4.2.1
• 4.2.2
• 4.2.3

License

• open-source

Website

• Vendor: https://www.apache.org/

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