CVE-2026-109391
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.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
Propose a mitigation on Community Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
References
- https://github.com/SquareSquash/web
- https://github.com/SquareSquash/web/blob/e73f2805f9eb30780a5c213b001f0f4255660fbf/app/controllers/api/v1_controller.rb
- https://github.com/SquareSquash/web/blob/e73f2805f9eb30780a5c213b001f0f4255660fbf/app/models/symbolication.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://hackmd.io/@1ExmmukzRMWN7B4gQ4W-4Q/HJ87QX5ifg
- https://www.vulncheck.com/advisories/square-squash-through-commit-e73f280-unauthenticated-yaml-deserialization-via-symbolication-api
CWEs
CWE-502
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.