GNU Mailman 2.1.39 Email Subject os command injection

Summaryinfo

A vulnerability classified as critical has been found in GNU Mailman 2.1.39. Affected by this vulnerability is an unknown functionality of the component Email Subject Handler. Performing a manipulation results in os command injection. This vulnerability is known as CVE-2025-43920. Remote exploitation of the attack is possible. No exploit is available.

Detailsinfo

A vulnerability was found in GNU Mailman 2.1.39. It has been classified as critical. This affects some unknown processing of the component Email Subject Handler. The manipulation with an unknown input leads to a os command injection vulnerability. CWE is classifying the issue as CWE-78. The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

GNU Mailman 2.1.39, as bundled in cPanel (and WHM), allows unauthenticated attackers to execute arbitrary OS commands via shell metacharacters in an email Subject line.

The advisory is shared at code.launchpad.net. This vulnerability is uniquely identified as CVE-2025-43920 since 04/19/2025. The exploitability is told to be difficult. 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 09/11/2025). MITRE ATT&CK project uses the attack technique T1202 for this issue.

The vulnerability scanner Nessus provides a plugin with the ID 264377 (Linux Distros Unpatched Vulnerability : CVE-2025-43920), which helps to determine the existence of the flaw in a target environment.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the databases at Tenable (264377) and EUVD (EUVD-2025-12591). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Type

• Mail Client Software

Vendor

• GNU

Name

• Mailman

Version

• 2.1.39

License

• open-source

Website

• Vendor: https://www.gnu.org/

CPE 2.3info

• 🔍

CPE 2.2info

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Entryinfo

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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