Raw vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:NSummary
CVE-2025-43920 is a medium-severity OS Command Injection (CWE-78) vulnerability in Gnu Mailman. Its CVSS base score is 5.4 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Command and Scripting Interpreter (T1059); ranked at the 44th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
GNU Mailman 2.1.39, as included in cPanel and WHM installations, contains an OS command injection flaw (CWE-78) that affects certain external archiver configurations. The vulnerability permits unauthenticated remote attackers to supply shell metacharacters in an email Subject header, resulting in arbitrary command execution on the underlying system. The issue carries a CVSS 3.1 score of 5.4 reflecting high attack complexity and limited impact scope.
An attacker can exploit the flaw by sending a single crafted email whose Subject line reaches the archiver code path; successful exploitation yields limited confidentiality and integrity impact without requiring authentication or user interaction. Multiple third-party reports indicate the condition could not be reproduced under either cPanel or standalone Mailman deployments.
Public references include the upstream Mailman 2.1 branch, a cPanel-specific Python 3 port, an oss-security disclosure thread, and a proof-of-concept repository. No official patch or configuration workaround details are provided in the available references. The associated EPSS score remains low, with a current value of 0.0096 and a peak of 0.0137.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2025-12591
Vulnerability Data
GNU Mailman 2.1.39, as bundled in cPanel (and WHM), in certain external archiver configurations, allows unauthenticated attackers to execute arbitrary OS commands via shell metacharacters in an email Subject line. NOTE: multiple third parties report that they are unable to…
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reproduce this, regardless of whether cPanel or WHM is used.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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V1.2.5V1.2.8V15.2.5
Mitigating Controls (NIST 800-53 r5) AI
Developer testing and evaluation can discover missing or incorrect command sanitization during development.
Input validation directly neutralizes or rejects special characters that would otherwise alter OS command structure.
Least privilege reduces the permissions available to any process that could be subverted by injected commands.
Least functionality restricts available OS commands and interpreters, limiting the blast radius of injection.
Secure engineering principles require proper neutralization of untrusted input before command construction.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
PR.PS-06's SDLC practices directly require secure coding and input handling that blocks command-injection defects, yet the single broad outcome leaves many specific neutralization vectors and verification gaps unaddressed.
Routine patching/maintenance can remediate known command-injection CVEs in dependencies (partial forward) but does nothing to stop developers from introducing improper neutralization in custom code (none reverse).
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing and code review target insecure use of operating-system command interfaces, catching command-injection flaws introduced during development.