GHSA-jm8c-9f3j-4378
MEDIUMGHSA-jm8c-9f3j-4378 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in pretalx. O3 Security confirms whether GHSA-jm8c-9f3j-4378 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
pretalx mail templates vulnerable to email injection via unescaped user-controlled placeholders
Real-World Exposure
pretalxReal-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
An unauthenticated attacker can send arbitrary HTML-rendered emails from a pretalx instance's configured sender address by embedding malformed HTML or markdown link syntax in a user-controlled template placeholder such as the account display name. The most direct vector is the password-reset flow: the attacker registers an account with a malicious name, enters the victim's email address, and triggers a password reset. The resulting email is delivered from the event's legitimate sender address and passes SPF/DKIM/DMARC validation, making it a ready-made phishing vector.
The same class of bug affects every mail template that interpolates a user-controlled placeholder (speaker name, proposal title, biography, question answers, etc.), including organiser-triggered emails such as acceptance/rejection notifications.
Credits
Thanks go to Mark Fijneman for finding and reporting a subset of this issue, which alerted us to the wider vulnerability.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | pretalx | all versions | 2026.1.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for pretalx. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update pretalx to 2026.1.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-jm8c-9f3j-4378 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 pinpoints whether GHSA-jm8c-9f3j-4378 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-jm8c-9f3j-4378. 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-jm8c-9f3j-4378 in your dependencies?
O3 detects GHSA-jm8c-9f3j-4378 across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.