User enumeration in Symfony

1) Observable response discrepancy

EUVDB-ID: #VU53200

Risk: Low

CVSSv3.1: 3.2 [CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-21424

CWE-ID: CWE-204 - Observable Response Discrepancy

Exploit availability: No

Description

The vulnerability allows a remote attacker to enumerate application users.

The vulnerability exists due to application returns different responses based on presence of user account name in application database. A remote attacker enumerate application users.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Symfony: 3.0.0 - 5.2.7

External links

http://github.com/symfony/symfony/releases/tag/v3.4.48
http://github.com/symfony/symfony/releases/tag/v5.2.8
http://github.com/symfony/symfony/releases/tag/v4.4.23

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.