CVE-2023-46733 is a medium-severity (CVSS 6.5) CWE-384 vulnerability in symfony/security-http. A fix is available for symfony/security-http — see the affected versions and patch details below.
Symfony possible session fixation vulnerability
Exploitation Status
No confirmed exploitation observed yet
- 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-2023-46733.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
symfony/security-http🐘symfony/security-http🐘symfony/symfony🐘symfony/symfonyReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | symfony/security-http | ≥ 5.4.21&&< 5.4.31 | 5.4.31composer require symfony/security-http:^5.4.31 |
| 🐘Packagist | symfony/security-http | ≥ 6.2.7&&< 6.3.8 | 6.3.8composer require symfony/security-http:^6.3.8 |
| 🐘Packagist | symfony/symfony | ≥ 5.4.21&&< 5.4.31 | 5.4.31composer require symfony/symfony:^5.4.31 |
| 🐘Packagist | symfony/symfony | ≥ 6.2.7&&< 6.3.8 | 6.3.8composer require symfony/symfony:^6.3.8 |
Affected Products
symfonysensiolabsDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for symfony/security-http, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update symfony/security-http to 5.4.31 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-46733 is resolved across your whole dependency graph.
Workarounds
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.
Frequently Asked Questions
Is CVE-2023-46733 in your dependencies?
Find it across Packagist, including transitive dependencies.