User enumeration in Symfony

1) Observable response discrepancy

EUVDB-ID: #VU53200

Risk: Low

CVSSv4.0: 1.7 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear]

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

CPE2.3

• cpe:2.3:a:sensiolabs:symfony:3.0.0:*:*:*:*:*:*:*
• cpe:2.3:a:sensiolabs:symfony:3.0.0-1:*:*:*:*:*:*:*
• cpe:2.3:a:sensiolabs:symfony:3.0.01:*:*:*:*:*:*:*

External links

https://github.com/symfony/symfony/releases/tag/v3.4.48
https://github.com/symfony/symfony/releases/tag/v5.2.8
https://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.