CVE-2025-49136: listmonk's Sprig template Injection vulnerability leads to reading of Environment Variable for low privilege user

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.6% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2025-06-09 · updated 2026-06-17
Weakness: CWE-1336

Description

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 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.

Affected products

knadh listmonk: from 4.0.0 before 5.0.2 — fixed in 5.0.2

How to fix

Upgrade to a fixed version: knadh listmonk 5.0.2. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2025-49136 or the next vulnerability affects your stack