CVE-2026-109391
8.1, highSquare Squash Deserialization of Untrusted Data Vulnerability
- CVSS
- 8.1, high high CVSS v3.1
- EPSS, next 30 days
- 0.5% higher than 39.7% of scored CVEs
- Exploitation
- No public evidence
- Published
- 12 Oct 20265 days ago
Description
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.
Details
- Vendor
- Square
- Product
- Squash
- Weakness
- CWE-502 (opens in a new tab)
- Status
- Received
- Updated
- 12 Oct 2026
- Assigner
- disclosure@vulncheck.com
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
References 7
Other references 7
- github.com /SquareSquash/web (opens in a new tab)
- github.com /SquareSquash/web/blob/e73f2805f9eb30780a5c213b001f0f4255660fbf/app/controllers/api/v1_controller.rb (opens in a new tab)
- github.com /SquareSquash/web/blob/e73f2805f9eb30780a5c213b001f0f4255660fbf/app/models/symbolication.rb (opens in a new tab)
- github.com /SquareSquash/web/blob/e73f2805f9eb30780a5c213b001f0f4255660fbf/config/preinitializers/safe_yaml.rb (opens in a new tab)
- github.com /SquareSquash/web/blob/e73f2805f9eb30780a5c213b001f0f4255660fbf/lib/workers/symbolication_creator.rb (opens in a new tab)
- hackmd.io /@1ExmmukzRMWN7B4gQ4W-4Q/HJ87QX5ifg (opens in a new tab)
- vulncheck.com /advisories/square-squash-through-commit-e73f280-unauthenticated-yaml-deserialization-via-symbolication-api (opens in a new tab)
The kind is read from NVD's tags where present and from the shape of the URL otherwise, so treat it as a hint.
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Assembled from the NVD 2.0 API, the CISA Known Exploited Vulnerabilities Catalog and FIRST EPSS. Scores are as of our last collection on 17 Oct 2026, not the live upstream state.