GHSA-6r2j-cxgf-495f
Parse Server vulnerable to session token exfiltration via `redirectClassNameForKey` query parameter
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
Weekly download volume for affected packages — a proxy for how broadly this vulnerability is deployed.
parse-servernpmDescription
Impact
A vulnerability in Parse Server's query handling allows an authenticated or unauthenticated attacker to exfiltrate session tokens of other users by exploiting the redirectClassNameForKey query parameter. Exfiltrated session tokens can be used to take over user accounts.
The vulnerability requires the attacker to be able to create or update an object with a new relation field, which depends on the Class-Level Permissions of at least one class.
Patches
The fix applies the same security checks that normally protect class access after the query redirect, ensuring that queries redirected via redirectClassNameForKey are subject to the same restrictions as direct queries to the target class.
Workarounds
Set restrictive Class-Level Permissions to prevent clients from creating new fields on classes, specifically by disabling addField for public access and unauthenticated users. Note that this limits client functionality and does not fully eliminate the risk if a relation field pointing to a protected class already exists in the schema.
References
- GitHub security advisory: https://github.com/parse-community/parse-server/security/advisories/GHSA-6r2j-cxgf-495f
- Fix Parse Server 9: https://github.com/parse-community/parse-server/releases/tag/9.5.2-alpha.8
- Fix Parse Server 8: https://github.com/parse-community/parse-server/releases/tag/8.6.21
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | parse-server | ≥ 9.0.0-alpha.1&&< 9.5.2-alpha.8 | 9.5.2-alpha.8 |
| 📦npm | parse-server | all versions | 8.6.21 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for parse-server. 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 parse-server to 9.5.2-alpha.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-6r2j-cxgf-495f 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-6r2j-cxgf-495f 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-6r2j-cxgf-495f. 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-6r2j-cxgf-495f in your dependencies?
O3 detects GHSA-6r2j-cxgf-495f across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.