{"cve":"CVE-2021-21424","nvd":{"published":"2021-05-13T16:15:07.777","modified":"2026-06-17T03:35:32.947","status":"Modified","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","score":5.3},"cwes":["CWE-203","CWE-200"],"references":["https://github.com/symfony/symfony/commit/2a581d22cc621b33d5464ed65c4bc2057f72f011","https://github.com/symfony/symfony/security/advisories/GHSA-5pv8-ppvj-4h68","https://lists.debian.org/debian-lts-announce/2023/07/msg00014.html","https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/KENRNLB3FYXYGDWRBH2PDBOZZKOD7VY4/","https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RH7TMM5CHQYBFFGXWRPJDPB3SKCZXI2M/"],"products":["fedoraproject:fedora","sensiolabs:symfony"],"source":"nvd","synced_at":"2026-10-19T21:18:09.669877188+00:00"},"epss":{"cve":"CVE-2021-21424","score":0.01644,"percentile":0.76441,"date":"2026-11-01"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}