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CVE-2025-49136VulnerabilityPublished

CVE-2025-49136: knadh listmonk · Improper Neutralization of Special Elements Used in a Template Engine

Affects knadh listmonkSource CVE Database V5

0

Not known to be exploited · public exploit available (Metasploit) · CVSS 9.1 Critical : upgrade to 5.0.2 as a priority.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 3.1 base score
9.1Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
1.5% chance of exploitation in 30 days – higher than 75% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 5.0.2
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 9 Jun 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: evidence found.

    1 Metasploit module

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.

What to do

Upgrade knadh/listmonk to 5.0.2.

Affected software

ProductAffectedFixed in
GitHubknadh/listmonkpkg:github/knadh/listmonkOther threatsAffected
  • <5.0.2 >=4.0.0
Fixed in
  • 5.0.2

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

1. Immediate upgrade to listmonk version 5.0.2 or later, where the vulnerability is fixed. 2. Until upgrade is possible, restrict campaign and template editing permissions strictly to super-admin or highly trusted users to prevent exploitation by lower-privileged users. 3. Review and minimize environment variables exposed to the listmonk process, removing any unnecessary sensitive data. 4. Implement network segmentation and access controls to isolate listmonk servers from critical infrastructure and sensitive data stores. 5. Monitor logs and template changes for suspicious use of '{{ env }}' or similar expressions indicative of exploitation attempts. 6. Conduct internal audits of user roles and permissions regularly to ensure least privilege principles are enforced. 7. Consider deploying runtime application self-protection (RASP) or web application firewalls (WAF) with custom rules to detect and block malicious template expressions if feasible. 8. Educate administrators and developers about secure template usage and the risks of exposing environment variables in multi-user environments.

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.

References

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