Advisory details:
github_osv / GHSA-c2p3-7m5p-cv8x
| Advisory ID | github_osv/GHSA-c2p3-7m5p-cv8x |
| Aliases |
CVE-2026-45133
|
| Summary | Symfony hardened the parser when handling untrusted input ### Description `Symfony\Component\Yaml\Parser` is the entry point for parsing YAML strings into PHP values via `Yaml::parse()`. When the parser is exposed to attacker-controlled input, deeply nested mappings or sequences cause both the block-level (`Parser::parseBlock()`) and inline (`Inline::parseSequence()` / `Inline::parseMapping()`) parsers to recurse without a depth limit. A crafted document exhausts the PHP stack and crashes the worker. ### Resolution The `Parser` now tracks recursion depth in a shared `ParserState` object across both block-level and inline parsing, with a default limit of **128**. The limit is configurable via a new `$maxNestingLevel` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. The patch for this issue is available [here](https://github.com/symfony/symfony/commit/914f427ed9630ddb3904dafba763e53d9f133fe3) for branch 5.4. ### Credits Symfony would like to thank Pietro Tirenna (Shielder) for reporting the issue and Nicolas Grekas for fixing it. |
| Status | Published |
| Exploitability | 0.5 |
| Weighted Severity | 2.4 |
| Risk | 1.2 |
| Affected and Fixed Packages | Package Details |
| Introduced and Fixed Package Commit Patches | Package Commit Patches Details |
| System | Score | Found at |
|---|---|---|
| cvssv4 | 2.7 | https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/05/GHSA-c2p3-7m5p-cv8x/GHSA-c2p3-7m5p-cv8x.json |
| generic_textual | LOW |
No EPSS data available for this advisory.
| Patch URL | |
|---|---|
| There are no known patches. | |
| Attack Vector (AV) | Attack Complexity (AC) | Attack Requirements (AT) | Privileges Required (PR) | User Interaction (UI) | Vulnerable System Impact Confidentiality (VC) | Vulnerable System Impact Integrity (VI) | Vulnerable System Impact Availability (VA) | Subsequent System Impact Confidentiality (SC) | Subsequent System Impact Integrity (SI) | Subsequent System Impact Availability (SA) |
|---|---|---|---|---|---|---|---|---|---|---|
network adjacent local physical |
low high |
none present |
none low high |
none passive active |
high low none |
high low none |
high low none |
high low none |
high low none |
high low none |
Vector: SSVCv2/E:N/A:N/T:P/P:M/B:A/M:M/D:T/2026-07-15T13:25:18Z/
Decision: Track
Source URL: https://github.com/cisagov/vulnrichment/blob/develop/2026/45xxx/CVE-2026-45133.json
Source Advisory: vulnrichment/CVE-2026-45133
[{'Exploitation': 'none'},
{'Automatable': 'no'},
{'Technical Impact': 'partial'},
{'Mission Prevalence': 'minimal'},
{'Public Well-being Impact': 'material'},
{'Mission & Well-being': 'medium'}]