CVE-2026-33409 — parse-server
Fix: parse-community/parse-server@8d7df56CVE-2026-33409 is a Improper Authentication vulnerability in parse-server. A fix is available for parse-server — see the affected versions and patch details below.
Parse Server: Auth provider validation bypass on login via partial authData
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-33409.
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.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
parse-servernpmDescription
Impact
An authentication bypass vulnerability allows an attacker to log in as any user who has linked a third-party authentication provider, without knowing the user's credentials. The attacker only needs to know the user's provider ID to gain full access to their account, including a valid session token.
This affects Parse Server deployments where the server option allowExpiredAuthDataToken is set to true. The default value is false.
Patches
Auth providers are now always validated on login, regardless of the allowExpiredAuthDataToken setting. The option allowExpiredAuthDataToken has been deprecated and will be removed in a future major version.
Workarounds
Set allowExpiredAuthDataToken to false (the default) or remove the option from the server configuration.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | parse-server | ≥ 9.0.0&&< 9.6.0-alpha.41 | 9.6.0-alpha.41npm install parse-server@9.6.0-alpha.41 |
| 📦npm | parse-server | all versions | 8.6.52npm install parse-server@8.6.52 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for parse-server, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update parse-server to 9.6.0-alpha.41 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-33409 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 CVE-2026-33409 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-33409. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-33409 in your dependencies?
O3 Security finds CVE-2026-33409 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.