Prevent user enumeration using Guard or the new Authenticator-based Security
Priority LOW 27CWE-200Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Information disclosure
- Confidentiality · integrity · availability
- Low · None · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-200.
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.
Why it matters now
EPSS 0.01644 76th percentileScored 2026-11-07
Fix Fixed symfony (symfony): 3.4.48, 4.4.23, 5.2.8symfony/security (Packagist): 5.2.8, 3.4.49, 4.4.24+6 more products
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| symfony | symfony | 2.8.0 to before 3.4.48; 4.0.0 to before 4.4.23; 5.0.0 to before 5.2.8 | 3.4.48, 4.4.23, 5.2.8 | Patch available | CNA |
| — | symfony/security (Packagist) | 5.0.0 to before 5.2.8 | 5.2.8 | Patch available | GHSA-5pv8-ppvj-4h68 |
| — | symfony/security-guard (Packagist) | 2.8.0 to before 3.4.48 | 3.4.48 | Patch available | GHSA-5pv8-ppvj-4h68 |
| — | symfony/security-guard (Packagist) | 4.0.0 to before 4.4.23 | 4.4.23 | Patch available | GHSA-5pv8-ppvj-4h68 |
| — | symfony/security-guard (Packagist) | 5.0.0 to before 5.2.8 | 5.2.8 | Patch available | GHSA-5pv8-ppvj-4h68 |
| — | symfony/security-core (Packagist) | 2.8.0 to before 3.4.48 | 3.4.48 | Patch available | GHSA-5pv8-ppvj-4h68 |
| — | symfony/security-core (Packagist) | 4.0.0 to before 4.4.23 | 4.4.23 | Patch available | GHSA-5pv8-ppvj-4h68 |
| — | symfony/security-core (Packagist) | 5.0.0 to before 5.2.8 | 5.2.8 | Patch available | GHSA-5pv8-ppvj-4h68 |
| — | lexik/jwt-authentication-bundle (Packagist) | 2.0.0 to before 2.10.7 | 2.10.7 | Patch available | GHSA-5pv8-ppvj-4h68 |
| — | lexik/jwt-authentication-bundle (Packagist) | 2.11.0 to before 2.11.3 | 2.11.3 | Patch available | GHSA-5pv8-ppvj-4h68 |
| — | symfony/maker-bundle (Packagist) | 1.27.0 to before 1.29.2 | 1.29.2 | Patch available | GHSA-5pv8-ppvj-4h68 |
| — | symfony/maker-bundle (Packagist) | 1.30.0 to before 1.31.1 | 1.31.1 | Patch available | GHSA-5pv8-ppvj-4h68 |
| — | symfony/security-http (Packagist) | 5.1.0 to before 5.2.8 | 5.2.8 | Patch available | GHSA-5pv8-ppvj-4h68 |
| — | symfony/security (Packagist) | 2.8.0 to before 3.4.49 | 3.4.49 | Patch available | GHSA-5pv8-ppvj-4h68 |
| — | symfony/security (Packagist) | 4.0.0 to before 4.4.24 | 4.4.24 | Patch available | GHSA-5pv8-ppvj-4h68 |
| — | symfony/symfony (Packagist) | 2.8.0 to before 3.4.49 | 3.4.49 | Patch available | GHSA-5pv8-ppvj-4h68 |
| — | symfony/symfony (Packagist) | 4.0.0 to before 4.4.24 | 4.4.24 | Patch available | GHSA-5pv8-ppvj-4h68 |
| — | symfony/symfony (Packagist) | 5.0.0 to before 5.2.9 | 5.2.9 | Patch available | GHSA-5pv8-ppvj-4h68 |
- symfony Vendorsymfony Affected 2.8.0 to before 3.4.48; 4.0.0 to before 4.4.23; 5.0.0 to before 5.2.8 Fixed in 3.4.48, 4.4.23, 5.2.8 Patch available CNA
- symfony/security (Packagist) Vendor— Affected 5.0.0 to before 5.2.8 Fixed in 5.2.8 Patch available GHSA-5pv8-ppvj-4h68
- symfony/security-guard (Packagist) Vendor— Affected 2.8.0 to before 3.4.48 Fixed in 3.4.48 Patch available GHSA-5pv8-ppvj-4h68
- symfony/security-guard (Packagist) Vendor— Affected 4.0.0 to before 4.4.23 Fixed in 4.4.23 Patch available GHSA-5pv8-ppvj-4h68
- symfony/security-guard (Packagist) Vendor— Affected 5.0.0 to before 5.2.8 Fixed in 5.2.8 Patch available GHSA-5pv8-ppvj-4h68
- symfony/security-core (Packagist) Vendor— Affected 2.8.0 to before 3.4.48 Fixed in 3.4.48 Patch available GHSA-5pv8-ppvj-4h68
- symfony/security-core (Packagist) Vendor— Affected 4.0.0 to before 4.4.23 Fixed in 4.4.23 Patch available GHSA-5pv8-ppvj-4h68
- symfony/security-core (Packagist) Vendor— Affected 5.0.0 to before 5.2.8 Fixed in 5.2.8 Patch available GHSA-5pv8-ppvj-4h68
- lexik/jwt-authentication-bundle (Packagist) Vendor— Affected 2.0.0 to before 2.10.7 Fixed in 2.10.7 Patch available GHSA-5pv8-ppvj-4h68
- lexik/jwt-authentication-bundle (Packagist) Vendor— Affected 2.11.0 to before 2.11.3 Fixed in 2.11.3 Patch available GHSA-5pv8-ppvj-4h68
- symfony/maker-bundle (Packagist) Vendor— Affected 1.27.0 to before 1.29.2 Fixed in 1.29.2 Patch available GHSA-5pv8-ppvj-4h68
- symfony/maker-bundle (Packagist) Vendor— Affected 1.30.0 to before 1.31.1 Fixed in 1.31.1 Patch available GHSA-5pv8-ppvj-4h68
- symfony/security-http (Packagist) Vendor— Affected 5.1.0 to before 5.2.8 Fixed in 5.2.8 Patch available GHSA-5pv8-ppvj-4h68
- symfony/security (Packagist) Vendor— Affected 2.8.0 to before 3.4.49 Fixed in 3.4.49 Patch available GHSA-5pv8-ppvj-4h68
- symfony/security (Packagist) Vendor— Affected 4.0.0 to before 4.4.24 Fixed in 4.4.24 Patch available GHSA-5pv8-ppvj-4h68
- symfony/symfony (Packagist) Vendor— Affected 2.8.0 to before 3.4.49 Fixed in 3.4.49 Patch available GHSA-5pv8-ppvj-4h68
- symfony/symfony (Packagist) Vendor— Affected 4.0.0 to before 4.4.24 Fixed in 4.4.24 Patch available GHSA-5pv8-ppvj-4h68
- symfony/symfony (Packagist) Vendor— Affected 5.0.0 to before 5.2.9 Fixed in 5.2.9 Patch available GHSA-5pv8-ppvj-4h68
CPE configurations NVD · 3
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:sensiolabs:symfony:*:*:*:*:*:*:*:* | 2.8.0 to before 3.4.48; 4.0.0 to before 4.4.23; 5.0.0 to before 5.2.8 | Vulnerable | sensiolabs |
| cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:* | 33 | Vulnerable | Fedoraproject |
| cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:* | 34 | Vulnerable | Fedoraproject |
- cpe:2.3:a:sensiolabs:symfony:*:*:*:*:*:*:*:* Versions 2.8.0 to before 3.4.48; 4.0.0 to before 4.4.23; 5.0.0 to before 5.2.8 Vulnerable ·sensiolabs
- cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:* Versions 33 Vulnerable ·Fedoraproject
- cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:* Versions 34 Vulnerable ·Fedoraproject
Remediation
- Fix · CNA symfony (symfony) Fixed in 3.4.48, 4.4.23, 5.2.8
- Fix · GHSA-5pv8-ppvj-4h68 symfony/security (Packagist) Fixed in 5.2.8 Advisory →
- Fix · GHSA-5pv8-ppvj-4h68 symfony/security-guard (Packagist) Fixed in 3.4.48 Advisory →
- Fix · GHSA-5pv8-ppvj-4h68 symfony/security-guard (Packagist) Fixed in 4.4.23 Advisory →
- Fix · GHSA-5pv8-ppvj-4h68 symfony/security-guard (Packagist) Fixed in 5.2.8 Advisory →
- Fix · GHSA-5pv8-ppvj-4h68 symfony/security-core (Packagist) Fixed in 3.4.48 Advisory →
- Fix · GHSA-5pv8-ppvj-4h68 symfony/security-core (Packagist) Fixed in 4.4.23 Advisory →
- Fix · GHSA-5pv8-ppvj-4h68 symfony/security-core (Packagist) Fixed in 5.2.8 Advisory →
- Fix · GHSA-5pv8-ppvj-4h68 lexik/jwt-authentication-bundle (Packagist) Fixed in 2.10.7 Advisory →
- Fix · GHSA-5pv8-ppvj-4h68 lexik/jwt-authentication-bundle (Packagist) Fixed in 2.11.3 Advisory →
- Fix · GHSA-5pv8-ppvj-4h68 symfony/maker-bundle (Packagist) Fixed in 1.29.2 Advisory →
- Fix · GHSA-5pv8-ppvj-4h68 symfony/maker-bundle (Packagist) Fixed in 1.31.1 Advisory →
- Fix · GHSA-5pv8-ppvj-4h68 symfony/security-http (Packagist) Fixed in 5.2.8 Advisory →
- Fix · GHSA-5pv8-ppvj-4h68 symfony/security (Packagist) Fixed in 3.4.49 Advisory →
- Fix · GHSA-5pv8-ppvj-4h68 symfony/security (Packagist) Fixed in 4.4.24 Advisory →
- Fix · GHSA-5pv8-ppvj-4h68 symfony/symfony (Packagist) Fixed in 3.4.49 Advisory →
- Fix · GHSA-5pv8-ppvj-4h68 symfony/symfony (Packagist) Fixed in 4.4.24 Advisory →
- Fix · GHSA-5pv8-ppvj-4h68 symfony/symfony (Packagist) Fixed in 5.2.9 Advisory →
Vendor assessments
Timeline
- 2026-10-02 Threatist record created from CVE-2021-21424
- 2026-10-03 Alias added: GHSA-5pv8-ppvj-4h68
References
Patch 2
Advisory 5
Other 17
- [debian-lts-announce] 20230711 [SECURITY] [DLA 3493-1] symfony security update
- https://symfony.com/cve-2021-21424
- https://lists.fedoraproject.org/archives/list/[email protected]/message/VRUS2H2SSOQWNLBD35SKIWIDQEMV2PD3
- https://lists.fedoraproject.org/archives/list/[email protected]/message/UC7BND775DVZDQT3RMGD2HVB2PKLJDJW
- https://lists.fedoraproject.org/archives/list/[email protected]/message/RH7TMM5CHQYBFFGXWRPJDPB3SKCZXI2M
- https://lists.fedoraproject.org/archives/list/[email protected]/message/KENRNLB3FYXYGDWRBH2PDBOZZKOD7VY4
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/VRUS2H2SSOQWNLBD35SKIWIDQEMV2PD3
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UC7BND775DVZDQT3RMGD2HVB2PKLJDJW
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RH7TMM5CHQYBFFGXWRPJDPB3SKCZXI2M
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/KENRNLB3FYXYGDWRBH2PDBOZZKOD7VY4
- https://github.com/symfony/symfony
- https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/symfony/CVE-2021-21424.yaml
- https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/security/CVE-2021-21424.yaml
- https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/security-http/CVE-2021-21424.yaml
- https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/security-guard/CVE-2021-21424.yaml
- https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/maker-bundle/CVE-2021-21424.yaml
- https://github.com/FriendsOfPHP/security-advisories/blob/master/lexik/jwt-authentication-bundle/CVE-2021-21424.yaml
More symfony vulnerabilities
- TI-2024-33775 Ability to change environment from query in symfony/runtime CVSS 3.1HIGH 7.3
- TI-2026-34283 Twig: The `spaceless` filter implicitly marks its output as safe CVSS 4.0MEDIUM 5.1
- TI-2022-07667 Code injection in Twig CVSS 3.1CRITICAL 9.8
- TI-2018-10028 Twig before 2.4.4 allows Server-Side Template Injection (SSTI) via the search search_key… CVSS 3.0CRITICAL 9.8
- TI-2026-35851 Incorrect authorization in symfony CVSS 4.0HIGH 8.7
- TI-2026-35264 Improper input validation in symfony CVSS 4.0HIGH 8.3
Sources
- CVE-2021-21424 · CVE Program
- CVE-2021-21424 · NVD
- FIRST EPSS
- GHSA-5pv8-ppvj-4h68 · GitHub Advisory Database · CC BY 4.0
- CVE-2021-21424 · Red Hat security data · CC BY 4.0
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