Symfony Remember-Me: Persistent Tokens Let a User Log In as Someone Else

Published as "CVE-2024-51996: Authentication Bypass via persisted RememberMe cookie"

high Symfony Symfony components · Last reviewed Nov 9, 2026

CVE: CVE-2024-51996
GHSA: GHSA-cg23-qf8f-62rr
Packagist: PKSA-rqvm-b18n-vg69
Reported: Nov 13, 2024

Lets someone with a valid remember-me token log in as a different user in Symfony apps that store remember-me tokens with a token provider.

Affected and fixed versions

In 2 packages: symfony/security-http and symfony/symfony. Find the row for the version you run, and update to the release next to it.

If you run	Update to	Support
6.4.0 – 6.4.14	6.4.15	Supported
5.4.0 – 5.4.46	5.4.47	Supported

Show 7 older branches, no longer supported

7.0.0 – 7.0.x	7.1.8
7.1.0 – 7.1.7	7.1.8
6.0.0 – 6.0.x	6.4.15
6.1.0 – 6.1.x	6.4.15
6.2.0 – 6.2.x	6.4.15
6.3.0 – 6.3.x	6.4.15
5.3.0 – 5.3.x	5.4.47

Upgrade

Run the line for the branch you are on. 1 other package listed above is affected too; update it the same way.

composer require symfony/security-http:^6.4.15
composer require symfony/security-http:^5.4.47

What this means

In apps that keep remember-me tokens in storage, Symfony didn't check that a remember-me cookie belonged to the user it named. Someone holding a valid remember-me token could use it to be logged in as a different user. This is an authentication bypass.

Who is affected

Apps on symfony/security-http (or symfony/symfony) 5.3.0 and later, below 5.4.47, 6.4.15 or 7.1.8 for their branch, that use persistent remember-me tokens. That means a firewall whose remember_me settings include a token_provider, which makes Symfony use PersistentRememberMeHandler. Apps that use the default signature-based remember-me cookies, or no remember-me at all, are not affected.

What to do

Update to 5.4.47, 6.4.15 or 7.1.8. After the fix, PersistentRememberMeHandler checks that the user in the cookie owns the stored token. See Symfony's advisory and the fix.

Reported by Moritz Rauch of Pentryx AG.

Check your app with an agent

Paste this into a coding agent that can read your project, such as Claude Code, Codex or Amp. It checks your composer.lock against the versions above and tells you what to update, without changing anything.

Check whether the PHP project you have access to is affected by this security advisory, and tell me what to update. Do a read-only check: don't edit files, don't run composer update or composer require, and don't try to reproduce the flaw.

Advisory: Symfony Remember-Me: Persistent Tokens Let a User Log In as Someone Else (CVE-2024-51996, GHSA-cg23-qf8f-62rr)
Details: https://phpnews.net/security/symfony/ghsa-cg23-qf8f-62rr

Affected versions, as Composer constraints:
- symfony/security-http, symfony/symfony: >=5.3.0,<5.4.0|>=5.4.0,<5.4.47|>=6.0.0,<6.1.0|>=6.1.0,<6.2.0|>=6.2.0,<6.3.0|>=6.3.0,<6.4.0|>=6.4.0,<6.4.15|>=7.0.0,<7.1.0|>=7.1.0,<7.1.8

Fixed releases on branches that still get security fixes:
- 6.4.0 – 6.4.14: update to 6.4.15
- 5.4.0 – 5.4.46: update to 5.4.47

1. Find every composer.lock in the project outside vendor/ (a monorepo can have one per app) and read the installed version of each package above. Packages installed as dependencies of other packages count too.
2. Compare each installed version with its constraint: "|" separates alternative ranges, and "," means both bounds apply.
3. For each affected install, read "What this means" at https://phpnews.net/security/symfony/ghsa-cg23-qf8f-62rr and check whether the project meets the conditions it describes (a feature in use, a config value, a driver) (if that page won't load, use https://github.com/advisories/GHSA-cg23-qf8f-62rr). Say which conditions you could check and which you couldn't.
4. Report a table: lock file | package | installed version | affected (yes, no or unknown) | conditions met (yes, no or unknown) | update to | evidence. For each affected package, give the command that would fix it, without running it: composer update <package> --with-dependencies when it is only installed as a dependency of another package, or composer require with the fixed version when composer.json requires it directly. If the installed version is on a branch with no fixed release listed, say it needs a move to a newer branch.

Sources

← All Symfony advisories