GHSA-hj8m-9fhf-v7jp is a critical-severity (CVSS 10) vulnerability in fief-server. A fix is available for fief-server — see the affected versions and patch details below.
fief-server Server-Side Template Injection vulnerability
Real-World Exposure
fief-serverReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
Server-Side Template Injection
Overview of the Vulnerability
Server-Side Template Injection (SSTI) is a vulnerability within application templating engines where user input is improperly handled and is embedded into the template, possibly leading code being executed.
An attacker can use SSTI to execute code on the underlying system by manipulating values within the embedded template. When code is executed within the underlying system, it can allow an attacker to run permissioned commands under the exploited process, or exploit Cross-Site Scripting (XSS) to run code within the user's browser.
Business Impact
SSTI can lead to reputational damage for the business due to a loss in confidence and trust by users. If an attacker successfully executes code within the underlying system, it can result in data theft and indirect financial losses.
Steps to Reproduce
- Sign up and login to your account
- Use a browser to navigate to: email-templates {{URL}}
- put your payload in Edit Base template
{{ cycler.__init__.__globals__.os.popen('id').read() }}and you will se it will execute.
Payload:
{{ cycler.__init__.__globals__.os.popen('id').read() }}
Proof of Concept (PoC)
The screenshot(s) below demonstrates the SSTI:
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | fief-server | ≥ 0.19.0&&< 0.25.3 | 0.25.3pip install --upgrade 'fief-server==0.25.3' |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for fief-server, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update fief-server to 0.25.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-hj8m-9fhf-v7jp 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.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-hj8m-9fhf-v7jp can be triaged on real exposure rather than presence alone.
Tailored to GHSA-hj8m-9fhf-v7jp. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-hj8m-9fhf-v7jp in your dependencies?
O3 Security finds GHSA-hj8m-9fhf-v7jp across PyPI dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.