CVE-2023-29019 is a high-severity (CVSS 8.1) CWE-384 vulnerability in @fastify/passport. A fix is available for @fastify/passport — see the affected versions and patch details below.
Session fixation in fastify-passport
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-2023-29019.
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.
How urgent is this, really
CVE-2023-29019 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,333 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
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.
@fastify/passportnpmDescription
@fastify/passport is a port of passport authentication library for the Fastify ecosystem. Applications using @fastify/passport in affected versions for user authentication, in combination with @fastify/session as the underlying session management mechanism, are vulnerable to session fixation attacks from network and same-site attackers. fastify applications rely on the @fastify/passport library for user authentication. The login and user validation are performed by the authenticate function. When executing this function, the sessionId is preserved between the pre-login and the authenticated session. Network and same-site attackers can hijack the victim's session by tossing a valid sessionId cookie in the victim's browser and waiting for the victim to log in on the website. As a solution, newer versions of @fastify/passport regenerate sessionId upon login, preventing the attacker-controlled pre-session cookie from being upgraded to an authenticated session. Users are advised to upgrade. There are no known workarounds for this vulnerability.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @fastify/passport | all versions | 1.1.0npm install @fastify/passport@1.1.0 |
| 📦npm | @fastify/passport | ≥ 2.0.0&&< 2.3.0 | 2.3.0npm install @fastify/passport@2.3.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @fastify/passport, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update @fastify/passport to 1.1.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-29019 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-2023-29019 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2023-29019. 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-2023-29019 in your dependencies?
O3 Security finds CVE-2023-29019 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.