Description
An issue was discovered in the Ldap component in Symfony 2.8.x before 2.8.37, 3.3.x before 3.3.17, 3.4.x before 3.4.7, and 4.0.x before 4.0.7. It allows remote attackers to bypass authentication by logging in with a "null" password and valid username, which triggers an unauthenticated bind. NOTE: this issue exists because of an incomplete fix for CVE-2016-2403.
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 | 3.4.12+dfsg-1 | — |
| Debian 13 | symfony | 3.4.12+dfsg-1 | — |
| Debian 12 | symfony | 3.4.12+dfsg-1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 18.04 LTS | symfony | 3.4.6+dfsg-1ubuntu0.1+esm1 | USN-4836-1 |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| Packagist | symfony/security | >= 2.8.0, < 2.8.37 | 2.8.37 | GHSA-35c5-28pg-2qg4 |
| Packagist | symfony/security | >= 3.0.0, < 3.3.17 | 3.3.17 | GHSA-35c5-28pg-2qg4 |
| Packagist | symfony/security | >= 3.4.0, < 3.4.7 | 3.4.7 | GHSA-35c5-28pg-2qg4 |
| Packagist | symfony/security | >= 4.0.0, < 4.0.7 | 4.0.7 | GHSA-35c5-28pg-2qg4 |
| Packagist | symfony/security-core | >= 2.8.0, < 2.8.37 | 2.8.37 | GHSA-35c5-28pg-2qg4 |
| Packagist | symfony/security-core | >= 3.0.0, < 3.3.17 | 3.3.17 | GHSA-35c5-28pg-2qg4 |
| Packagist | symfony/security-core | >= 3.4.0, < 3.4.7 | 3.4.7 | GHSA-35c5-28pg-2qg4 |
| Packagist | symfony/security-core | >= 4.0.0, < 4.0.7 | 4.0.7 | GHSA-35c5-28pg-2qg4 |
| Packagist | symfony/symfony | >= 2.8.0, < 2.8.37 | 2.8.37 | GHSA-35c5-28pg-2qg4 |
| Packagist | symfony/symfony | >= 3.0.0, < 3.3.17 | 3.3.17 | GHSA-35c5-28pg-2qg4 |
| Packagist | symfony/symfony | >= 3.4.0, < 3.4.7 | 3.4.7 | GHSA-35c5-28pg-2qg4 |
| Packagist | symfony/symfony | >= 4.0.0, < 4.0.7 | 4.0.7 | GHSA-35c5-28pg-2qg4 |
Advisories 1
- USN-4836-1 symfony vulnerability Ubuntu Security Notices (USN) · Feb 10, 2026