CVE-2025-49136
Nadh Listmonk 4.0.0 – 5.0.2
Raw vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:HSummary
CVE-2025-49136 is a critical-severity Improper Neutralization of Special Elements Used in a Template Engine (CWE-1336) vulnerability in Nadh Listmonk. Its CVSS base score is 9.0 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Template Injection (T1221); ranked in the top 31% of CVEs by exploit likelihood; 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.
listmonk is a self-hosted newsletter and mailing list manager that is affected by CVE-2025-49136 in versions 4.0.0 through 5.0.1. The root cause is the default enabling of the env and expandenv template functions from the Sprig library, which permits arbitrary retrieval of host environment variables through template expressions such as {{ env }}. This occurs in the campaign and template handling components and is tracked under CWE-1336.
In multi-user deployments, any authenticated user granted campaign or template permissions can exploit the flaw to read sensitive environment variables, even without super-admin rights. The CVSS 9.0 score reflects a network-accessible attack with low complexity that can result in high impact to confidentiality, integrity, and availability when chained with other operations.
The official GitHub security advisory GHSA-jc7g-x28f-3v3h and release notes for v5.0.2 direct administrators to upgrade immediately; the patch disables or restricts the problematic template functions. The associated EPSS score has remained flat at 0.6176 with no indicated rise after disclosure.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2025-17462
Vulnerability Data
listmonk is a standalone, self-hosted, newsletter and mailing list manager. Starting in version 4.0.0 and prior to version 5.0.2, the `env` and `expandenv` template functions which is enabled by default in Sprig enables capturing of env variables on host. While…
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this may not be a problem on single-user (super admin) installations, on multi-user installations, this allows non-super-admin users with campaign or template permissions to use the `{{ env }}` template expression to capture sensitive environment variables. Users should upgrade to v5.0.2 to mitigate the issue.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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V1.3.2V1.3.7V1.3.10
Mitigating Controls (NIST 800-53 r5) AI
Developer testing and static analysis can discover missing neutralization of template directives.
Input validation rejects or sanitizes untrusted data before it reaches the template engine, stopping injection of special syntax.
Security engineering principles require use of safe templating APIs and proper escaping of external input.
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.
Secure SDLC practices directly require proper input neutralization in template engines to prevent injection.
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 can detect template-injection flaws but does not itself implement neutralization controls.
Secure development life cycle mandates input validation and sanitization that directly prevents template-injection weaknesses.
Application security requirements explicitly call for neutralizing special elements in template engines.
Secure architecture principles reduce the likelihood of unsafe template processing but do not prescribe specific neutralization techniques.
Secure coding standards require proper escaping or sandboxing of template directives, directly mitigating CWE-1336.