Description
An issue was discovered in Symfony 4.2.0 to 4.2.11 and 4.3.0 to 4.3.7. The ability to enumerate users was possible due to different handling depending on whether the user existed when making unauthorized attempts to use the switch users functionality. This is related to symfony/security.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | symfony | 4.3.8+dfsg-1 | — |
| Debian 13 | symfony | 4.3.8+dfsg-1 | — |
| Debian 12 | symfony | 4.3.8+dfsg-1 | — |
| Debian 8 | symfony | 2.3.21+dfsg-4+deb8u6 | DLA-1999-1 |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| Packagist | symfony/security-http | >= 4.1.0, < 4.2.12 | 4.2.12 | GHSA-4vpc-5jx4-cfqg |
| Packagist | symfony/security-http | >= 4.3.0, < 4.3.8 | 4.3.8 | GHSA-4vpc-5jx4-cfqg |
| Packagist | symfony/symfony | >= 4.1.0, < 4.2.12 | 4.2.12 | GHSA-4vpc-5jx4-cfqg |
| Packagist | symfony/symfony | >= 4.3.0, < 4.3.8 | 4.3.8 | GHSA-4vpc-5jx4-cfqg |
Advisories 1
- DLA-1999-1 symfony - security update Debian Security (DSA / DLA) · Mar 9, 2026