{"id":"CVE-2026-109391","aliases":[],"title":"Square Squash through commit e73f280 Unauthenticated YAML Deserialization via Symbolication API","titleSource":"VulnCheck","descriptionSource":"VulnCheck","products":[{"vendor":"Square","name":"Squash","platforms":[],"versions":[{"version":"0","status":"affected","lessThanOrEqual":"e73f2805f9eb30780a5c213b001f0f4255660fbf","versionType":"git"}],"defaultStatus":"unaffected","source":"VulnCheck","url":"https://www.cve.org/CVERecord?id=CVE-2026-109391"}],"remediation":[],"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.","severity":"critical","score":9.2,"published":"2026-10-12T15:16:39.257Z","modified":"2026-10-27T01:30:40.899Z","withdrawn":false,"knownExploited":false,"affected":[],"references":["https://hackmd.io/@1ExmmukzRMWN7B4gQ4W-4Q/HJ87QX5ifg","https://github.com/SquareSquash/web/blob/e73f2805f9eb30780a5c213b001f0f4255660fbf/app/controllers/api/v1_controller.rb","https://github.com/SquareSquash/web/blob/e73f2805f9eb30780a5c213b001f0f4255660fbf/config/preinitializers/safe_yaml.rb","https://github.com/SquareSquash/web/blob/e73f2805f9eb30780a5c213b001f0f4255660fbf/lib/workers/symbolication_creator.rb","https://github.com/SquareSquash/web/blob/e73f2805f9eb30780a5c213b001f0f4255660fbf/app/models/symbolication.rb","https://github.com/SquareSquash/web","https://www.vulncheck.com/advisories/square-squash-through-commit-e73f280-unauthenticated-yaml-deserialization-via-symbolication-api"],"sources":[{"name":"CVE","id":"CVE-2026-109391","modified":"2026-10-27T01:30:40.899Z","url":"https://www.cve.org/CVERecord?id=CVE-2026-109391"}],"assessments":[{"source":"VulnCheck","vector":"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","score":9.2},{"source":"VulnCheck","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H","score":8.1}],"sourceAffected":[],"kev":{"status":"not-listed","checkedAt":"2026-10-29T02:25:31.980Z"},"coverage":[{"source":"NVD","status":"not-checked"},{"source":"GHSA","status":"not-checked"},{"source":"EUVD","status":"not-checked"},{"source":"EPSS","status":"not-checked"}],"evidence":[]}