Prevent user enumeration using Guard or the new Authenticator-based Security
CVE-2021-21424

5.3MEDIUM

Key Information:

Vendor
Symfony
Status
Symfony
Vendor
CVE Published:
13 May 2021

Badges

👾 Exploit Exists🟡 Public PoC

Summary

Symfony is a PHP framework for web and console applications and a set of reusable PHP components. The ability to enumerate users was possible without relevant permissions due to different handling depending on whether the user existed or not when attempting to use the switch users functionality. We now ensure that 403s are returned whether the user exists or not if a user cannot switch to a user or if the user does not exist. The patch for this issue is available for branch 3.4.

Affected Version(s)

symfony >= 2.8.0, < 3.4.48 < 2.8.0, 3.4.48

symfony >= 4.0.0, < 4.4.23 < 4.0.0, 4.4.23

symfony >= 5.0.0, < 5.2.8 < 5.0.0, 5.2.8

Exploit Proof of Concept (PoC)

PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.

CVE-2021-21424
Created by moften

References

https://github.com/symfony/symfony/security/advisories/GH...
https://github.com/symfony/symfony/commit/2a581d22cc621b3...
https://lists.fedoraproject.org/archives/list/package-ann...
vendor-advisory

CVSS V3.1

Score:
5.3
Severity:
MEDIUM
Confidentiality:
Low
Integrity:
None
Availability:
Low
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • 🟡

    Public PoC available

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

.