Answer in brief
CVE-2026-109391 records a Critical severity (CVSS 9.2) vulnerability in Square Squash through commit e73f280 Unauthenticated YAML Deserialization via Symbolication API. The current sources do not mark it as known exploited. The current feed maps Square/Squash (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 9.2. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Square/Squash (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Square/Squashgeneric | >=0 <=e73f2805f9eb30780a5c213b001f0f4255660fbf | Not reported |
Published upstream
Oct 12, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 12, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Oct 12, 2026
Square Squash through commit e73f280 contains an insecure deserialization vulnerability that allows unauthenticated attackers to store crafted YAML via the POST /api/1.0/symbolication endpoint. When occurrences referencing the attacker-controlled symbolication UUID are symbolicated, the stored values are passed to YAML.load with SafeYAML in unsafe mode, enabling arbitrary Ruby object deserialization and potential code execution.
Quoted source text, attributed separately from HOL analysis.