Vulnerability details
CVE-2026-109391
square Squash
Square Squash through commit e73f280 Unauthenticated YAML Deserialization via Symbolication API
CVSS 4.0
9.2Critical
Official 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.
CVSS scores
| Score | Version | Source | Vector |
|---|---|---|---|
| 9.2Critical | 4.0 | CVEProject cvelistV5 (CNA) (VulnCheck) | CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N |
| 8.1High | 3.1 | CVEProject cvelistV5 (CNA) (VulnCheck) | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H |
Affected products
| Vendor | Product | Versions | Source |
|---|---|---|---|
| square | Squash | v ≤ e73f2805f9eb30780a5c213b001f0f4255660fbf | CVEProject cvelistV5 (CNA) |
References and advisories
7- https://hackmd.io/@1ExmmukzRMWN7B4gQ4W-4Q/HJ87QX5ifg technical-descriptionexploit
- https://github.com/SquareSquash/web/blob/e73f2805f9eb30780a5c213b001f0f4255660fbf/app/controllers/api/v1_controller.rb technical-description
- https://github.com/SquareSquash/web/blob/e73f2805f9eb30780a5c213b001f0f4255660fbf/config/preinitializers/safe_yaml.rb technical-description
- https://github.com/SquareSquash/web/blob/e73f2805f9eb30780a5c213b001f0f4255660fbf/lib/workers/symbolication_creator.rb technical-description
- https://github.com/SquareSquash/web/blob/e73f2805f9eb30780a5c213b001f0f4255660fbf/app/models/symbolication.rb technical-description
- https://github.com/SquareSquash/web product
- https://www.vulncheck.com/advisories/square-squash-through-commit-e73f280-unauthenticated-yaml-deserialization-via-symbolication-api third-party-advisory
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Details
- Published
- 2026-10-12
- Last updated
- 2026-10-27
- State
- Published
- Assigner (CNA)
- VulnCheck
- Kolun priority
- 34 · Low
Exploit prediction (EPSS)
0.47%
Probability of exploitation in 30 days
41.4%
Percentile (among all CVEs)
SSVC assessment (CISA)
- Automatable
- No
- Exploitation
- None
- Technical impact
- Total
Weaknesses (CWE)
- CWE-502Deserialization of Untrusted Data