Advisory details:
github_osv / GHSA-2v3c-qxhr-7vpv
| Advisory ID | github_osv/GHSA-2v3c-qxhr-7vpv |
| Aliases |
CVE-2026-109413
|
| Summary | Symfony: Unbounded Recursion in the YAML Inline Lexer Lets a Single Document Crash the Process ### Description `Yaml\Parser::lexInlineStructure()` recursed through `lexInlineMapping()` and `lexInlineSequence()` for every `{` and `[` of an inline collection, without entering the nesting level that the rest of the parser bounds with `maxNestingLevel`. A document made of deeply nested inline collections, such as `[[[[...]]]]`, exhausted the stack while it was being lexed: depending on the PHP version and its stack settings, the process crashed or the request ended with a fatal error. Any code parsing untrusted YAML is affected. That includes `#[MapRequestPayload]` when the Yaml component is installed and the endpoint does not restrict `acceptFormat`: a single unauthenticated request with a YAML content type is enough. ### Resolution The inline lexer now enters and leaves the same nesting level as the rest of the parser, so nested inline collections are bounded by `maxNestingLevel`, and the parser raises a `ParseException` beyond it. The patches for this issue are available [here](https://github.com/symfony/symfony/commit/2a8bf9c58d862b0c76a35ce288d1ba6a27223aad) for branch 5.4 (and forward-ported to 6.4, 7.4, 8.1 and 8.2). ### Credits We would like to thank Nicolas Grekas for reporting the issue and providing the fix. ### References - Fix: [#65688](https://github.com/symfony/symfony/pull/65688) |
| Status | Published |
| Exploitability | 0.5 |
| Weighted Severity | 7.8 |
| Risk | 3.9 |
| Affected and Fixed Packages | Package Details |
| Introduced and Fixed Package Commit Patches | Package Commit Patches Details |
| CWE-674 | Uncontrolled Recursion |
| System | Score | Found at |
|---|---|---|
| cvssv4 | 8.7 | https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-2v3c-qxhr-7vpv/GHSA-2v3c-qxhr-7vpv.json |
| generic_textual | HIGH |
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 |
There are no SSVC decisions available.