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GHSA-2ffv-r4r9-r8xrcritical

Laravel RCE vulnerability in "cookie" session driver

No CVE assignedCheck your stack

Impact

Application's using the "cookie" session driver were the primary applications affected by this vulnerability. Since we have not yet released a security release for the Laravel 5.5 version of the framework, we recommend that all applications running Laravel 5.5 and earlier do not use the "cookie" session driver in their production deployments.

Source excerpt · OSV

Affected packages

Start with the recorded fix for your release branch. Check your installed version and test compatibility before upgrading. Fixing this advisory does not rule out other vulnerabilities in the release.

Affected rangeRecorded fix
From 4.1.0 before 6.18.31Ecosystem versions6.18.31
From 7.0.0 before 7.22.4Ecosystem versions7.22.4

Version evidence: OSV · GHSA-2ffv-r4r9-r8xr

View original version evidence (307 explicit versions)

Original source description

Application's using the "cookie" session driver were the primary applications affected by this vulnerability. Since we have not yet released a security release for the Laravel 5.5 version of the framework, we recommend that all applications running Laravel 5.5 and earlier do not use the "cookie" session driver in their production deployments.

Regarding the vulnerability, applications using the "cookie" session driver that were also exposing an encryption oracle via their application were vulnerable to remote code execution. An encryption oracle is a mechanism where arbitrary user input is encrypted and the encrypted string is later displayed or exposed to the user. This combination of scenarios lets the user generate valid Laravel signed encryption strings for any plain-text string, thus allowing them to craft Laravel session payloads when an application is using the "cookie" driver.

This fix prefixes cookie values with an HMAC hash of the cookie's name before encryption and then verifies a matching hash on decryption, making it impossible to craft a valid cookie payload even if an encryption oracle is exposed via the application.

References