CVE-2025-49136 is a critical-severity (CVSS 9) CWE-1336 vulnerability in github.com/knadh/listmonk. A fix is available for github.com/knadh/listmonk — see the affected versions and patch details below.
listmonk's Sprig template Injection vulnerability leads to reading of Environment Variable for low privilege user
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA’s SSVC triage for CVE-2025-49136.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
github.com/knadh/listmonkReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Summary
The env and expandenv template functions which is enabled by default in Sprig enables capturing of env variables on the 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.
Upgrade to v5.0.2 to mitigate.
Demonstration
Description
A critical template injection vulnerability exists in Listmonk's campaign preview functionality that allows authenticated users with minimal privileges (campaigns:get & campaigns:get_all) to extract sensitive system data, including database credentials, SMTP passwords, and admin credentials due to some dangerous function being allowed.
Proof of Concept
- Create a user and give him
campaigns:getandcampaigns:get_allprivileges
-
Now login with that user, go to any campaign, go the Content section and here lies the vulnerability, we're able to execute template content which allows us to get environment variables, execute Sprig functions...
-
Now in the text field you can input the following and press Preview:
{{ env "AWS_KEY" }}
{{ env "LISTMONK_db__user" }}
{{ env "LISTMONK_db__password" }}
Preview:
I had the AWS_KEY variable set like that to confirm the vulnerability:
Impact
- Through these environment variables the attacker can access, they can fully compromise the database, cloud accounts, admin credentials, and more depending on what was setup leading to total system takeover and data breach.
Suggested Fix
- Blacklist some function for templates like env, expandEnv and fail as they can be used to leak environment variables which leads to a full takeover.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/knadh/listmonk | ≥ 4.0.0&&< 5.0.2 | 5.0.2go get github.com/knadh/listmonk@v5.0.2 |
Affected Products
listmonknadhDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/knadh/listmonk, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/knadh/listmonk to 5.0.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-49136 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Frequently Asked Questions
Is CVE-2025-49136 in your dependencies?
Find it across Go, including transitive dependencies.