CVE-2026-45304
low
CVSS v3
—
CVSS v4 NEW
—
VIR risk
2.5
Description
Symfony's YAML Parser Vulnerable to Exponential Memory Allocation via Recursive Collection-Alias Expansion ("Billion Laughs")
Predictions
Exploit likelihood
20%
Patch ETA
—
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
OS impact
Debian Mixed 5 releases
| Version | Status | Fixed in |
|---|---|---|
| trixie | Fixed | 6.4.41+dfsg-0+deb13u1 |
| sid | Fixed | 7.4.12+dfsg-1 |
| forky | Fixed | 7.4.12+dfsg-1 |
| bullseye | Affected | — |
| bookworm | Fixed | 5.4.53+dfsg-0+deb12u1 |
Package impact
| Ecosystem | Package | Vulnerable | Fixed |
|---|---|---|---|
| Packagist | symfony/yaml | >=2.0.0,<3.0.0|>=3.0.0,<4.0.0|>=4.0.0,<5.0.0|>=5.0.0,<5.1.0|>=5.1.0,<5.2.0|>=5.2.0,<5.3.0|>=5.3.0,<5.4.0|>=5.4.0,<5.4.52|>=6.0.0,<6.1.0|>=6.1.0,<6.2.0|>=6.2.0,<6.3.0|>=6.3.0,<6.4.0|>=6.4.0,<6.4.40|>=7.0.0,<7.1.0|>=7.1.0,<7.2.0|>=7.2.0,<7.3.0|>=7.3.0,<7.4.0|>=7.4.0,<7.4.12|>=8.0.0,<8.0.12 | |
| Packagist | symfony/symfony | >=2.0.0,<3.0.0|>=3.0.0,<4.0.0|>=4.0.0,<5.0.0|>=5.0.0,<5.1.0|>=5.1.0,<5.2.0|>=5.2.0,<5.3.0|>=5.3.0,<5.4.0|>=5.4.0,<5.4.52|>=6.0.0,<6.1.0|>=6.1.0,<6.2.0|>=6.2.0,<6.3.0|>=6.3.0,<6.4.0|>=6.4.0,<6.4.40|>=7.0.0,<7.1.0|>=7.1.0,<7.2.0|>=7.2.0,<7.3.0|>=7.3.0,<7.4.0|>=7.4.0,<7.4.12|>=8.0.0,<8.0.12 | |
| COMPOSER | symfony/yaml | >= 8.0.0, < 8.0.12 | 8.0.12 |
| COMPOSER | symfony/yaml | >= 7.0.0, < 7.4.12 | 7.4.12 |
| COMPOSER | symfony/yaml | >= 6.0.0, < 6.4.40 | 6.4.40 |
| COMPOSER | symfony/symfony | >= 8.0.0, < 8.0.12 | 8.0.12 |
| COMPOSER | symfony/symfony | >= 7.0.0, < 7.4.12 | 7.4.12 |
| COMPOSER | symfony/symfony | >= 6.0.0, < 6.4.40 | 6.4.40 |
| COMPOSER | symfony/symfony | < 5.4.52 | 5.4.52 |
| COMPOSER | symfony/yaml | < 5.4.52 | 5.4.52 |
| Packagist | symfony/yaml | <5.4.52 | 5.4.52 |
| Packagist | symfony/symfony | <5.4.52 | 5.4.52 |
| Packagist | symfony/symfony | >=6.0.0,<6.4.40 | 6.4.40 |
| Packagist | symfony/symfony | >=7.0.0,<7.4.12 | 7.4.12 |
| Packagist | symfony/symfony | >=8.0.0,<8.0.12 | 8.0.12 |
| Packagist | symfony/yaml | >=6.0.0,<6.4.40 | 6.4.40 |
| Packagist | symfony/yaml | >=7.0.0,<7.4.12 | 7.4.12 |
| Packagist | symfony/yaml | >=8.0.0,<8.0.12 | 8.0.12 |
References
- https://symfony.com/cve-2026-45304
- https://security-tracker.debian.org/tracker/CVE-2026-45304
- https://github.com/symfony/symfony/security/advisories/GHSA-4qpc-3hr4-r2p4
- https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573674c8ed4a970a
- https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/symfony/CVE-2026-45304.yaml
- https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/yaml/CVE-2026-45304.yaml
- https://github.com/advisories/GHSA-4qpc-3hr4-r2p4
- https://github.com/symfony/symfony
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.