CVE-2026-45304
published 2026-07-14CVE-2026-45304: Symfony is a PHP framework for web and console applications and a set of reusable PHP components. Prior to 5.4.52, 6.4.40, 7.4.12, and 8.0.12…
PriorityP346high7.5CVSS 3.1
AVNACLPRNUINSUCNINAH
EPSS
0.80%
53.0th percentile
Symfony is a PHP framework for web and console applications and a set of reusable PHP components. Prior to 5.4.52, 6.4.40, 7.4.12, and 8.0.12, Symfony\Component\Yaml\Parser resolved YAML collection aliases recursively, allowing a small untrusted YAML input to expand into a multi-gigabyte structure and exhaust memory. This issue is fixed in versions 5.4.52, 6.4.40, 7.4.12, and 8.0.12.
Affected
20 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| sensiolabs | symfony | < 5.4.52 | 5.4.52 |
| sensiolabs | symfony | >= 6.0.0 < 6.4.40 | 6.4.40 |
| sensiolabs | symfony | >= 7.0.0 < 7.4.12 | 7.4.12 |
| sensiolabs | symfony | >= 8.0.0 < 8.0.12 | 8.0.12 |
| symfony | symfony | < 5.4.52 | 5.4.52 |
| symfony | symfony | — | — |
| symfony | symfony | — | — |
| symfony | symfony | — | — |
| symfony | symfony | >= 0 < 5.4.52 | 5.4.52 |
| symfony | symfony | >= 6.0.0 < 6.4.40 | 6.4.40 |
| symfony | symfony | >= 7.0.0 < 7.4.12 | 7.4.12 |
| symfony | symfony | >= 8.0.0 < 8.0.12 | 8.0.12 |
| symfony | yaml | < 5.4.52 | 5.4.52 |
| symfony | yaml | — | — |
| symfony | yaml | — | — |
| symfony | yaml | — | — |
| symfony | yaml | >= 0 < 5.4.52 | 5.4.52 |
| symfony | yaml | >= 6.0.0 < 6.4.40 | 6.4.40 |
| symfony | yaml | >= 7.0.0 < 7.4.12 | 7.4.12 |
| symfony | yaml | >= 8.0.0 < 8.0.12 | 8.0.12 |
CVSS provenance
nvdv3.17.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
nvdv4.08.7HIGHCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
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VulDB
Symfony YAML Parser allocation of resources
vuldb·2026-05-28
CVE-2026-45304 [LOW] Symfony YAML Parser allocation of resources
A vulnerability was found in Symfony. It has been classified as problematic. This impacts an unknown function of the component YAML Parser. Performing a manipulation results in allocation of resources.
This vulnerability was named CVE-2026-45304. The attack may be initiated remotely. There is no available exploit.
Upgrading the affected component is recommended.
GHSA
Symfony's YAML Parser Vulnerable to Exponential Memory Allocation via Recursive Collection-Alias Expansion ("Billion Laughs")
ghsa·2026-05-27
CVE-2026-45304 [LOW] CWE-776 Symfony's YAML Parser Vulnerable to Exponential Memory Allocation via Recursive Collection-Alias Expansion ("Billion Laughs")
Symfony's YAML Parser Vulnerable to Exponential Memory Allocation via Recursive Collection-Alias Expansion ("Billion Laughs")
### Description
`Symfony\Component\Yaml\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic "Billion Laughs" denial-of-service against any parser exposed to untrusted YAML.
### Resolution
The `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the [SnakeYAML model](https://github.com/snakeyaml
No detection rules found.
No public exploits indexed.
No writeups or analysis indexed.
https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573674c8ed4a970ahttps://github.com/symfony/symfony/releases/tag/v5.4.52https://github.com/symfony/symfony/releases/tag/v6.4.40https://github.com/symfony/symfony/releases/tag/v7.4.12https://github.com/symfony/symfony/releases/tag/v8.0.12https://github.com/symfony/symfony/security/advisories/GHSA-4qpc-3hr4-r2p4
2026-07-14
Published