CVE-2021-21424

unknown
Published 2021-05-13 · Modified 2026-03-13
CVSS v3
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
CVSS v2
VIR risk

Description

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.

Predictions

Exploit likelihood
30%
Patch ETA

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

vendor Authored 2026-05-27

Vendor advisory: debian — https://security-tracker.debian.org/tracker/CVE-2021-21424

OS impact

OSVersionStatusFixed in
debian debianbookwormfixed4.4.19+dfsg-2
debian debianbullseyefixed4.4.19+dfsg-2
debian debianforkyfixed4.4.19+dfsg-2
debian debiansidfixed4.4.19+dfsg-2
debian debiantrixiefixed4.4.19+dfsg-2

Package impact

EcosystemPackageVulnerableFixed
php Packagistsymfony/security>=5.0.0,<5.2.85.2.8
php Packagistsymfony/security-guard>=2.8.0,<3.4.483.4.48
php Packagistsymfony/security-guard>=4.0.0,<4.4.234.4.23
php Packagistsymfony/security-guard>=5.0.0,<5.2.85.2.8
php Packagistsymfony/security-core>=2.8.0,<3.4.483.4.48
php Packagistsymfony/security-core>=4.0.0,<4.4.234.4.23
php Packagistsymfony/security-core>=5.0.0,<5.2.85.2.8
php Packagistlexik/jwt-authentication-bundle>=2.0.0,<2.10.72.10.7
php Packagistlexik/jwt-authentication-bundle>=2.11.0,<2.11.32.11.3
php Packagistsymfony/maker-bundle>=1.27.0,<1.29.21.29.2
php Packagistsymfony/maker-bundle>=1.30.0,<1.31.11.31.1
php Packagistsymfony/security-http>=5.1.0,<5.2.85.2.8
php Packagistsymfony/security>=2.8.0,<3.4.493.4.49
php Packagistsymfony/security>=4.0.0,<4.4.244.4.24
php Packagistsymfony/symfony>=2.8.0,<3.4.493.4.49
php Packagistsymfony/symfony>=4.0.0,<4.4.244.4.24
php Packagistsymfony/symfony>=5.0.0,<5.2.95.2.9

References

Verify integrity in audit chain (admin only). AS-IS.