CVE-2026-109391CWE-502insecure-deserialization

CVE-2026-109391

High · published October 12, 2026

CVSS v3.1
8.1
EPSS
0%
Percentile
40.2
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
8.1 · HIGH
Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS v4.0
9.2 · 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
EPSS
0.00477 · 40.2th percentile
Weakness
CWE-502 · Deserialization of Untrusted Data
Published
2026-10-12T20:17Z
References (7)
https://github.com/SquareSquash/web · [email protected]https://github.com/SquareSquash/web/blob/e73f2805f9eb30780a5c213b001f0f4255660fbf/app/controllers/api/v1_controller.rb · [email protected]https://github.com/SquareSquash/web/blob/e73f2805f9eb30780a5c213b001f0f4255660fbf/app/models/symbolication.rb · [email protected]https://github.com/SquareSquash/web/blob/e73f2805f9eb30780a5c213b001f0f4255660fbf/config/preinitializers/safe_yaml.rb · [email protected]https://github.com/SquareSquash/web/blob/e73f2805f9eb30780a5c213b001f0f4255660fbf/lib/workers/symbolication_creator.rb · [email protected]https://hackmd.io/@1ExmmukzRMWN7B4gQ4W-4Q/HJ87QX5ifg · [email protected]https://www.vulncheck.com/advisories/square-squash-through-commit-e73f280-unauthenticated-yaml-deserialization-via-symbolication-api · [email protected]
EPSS history
Timeline
  • 14 OCT 03:27Z
    EPSS moved — → 0%
    epss
  • 12 OCT 15:16Z
    Square Squash through commit e73f280 Unauthenticated YAML Deserialization via Symbolication API
    cvelistv5
  • 12 OCT 15:16Z
    Square Squash through commit e73f280 Unauthenticated YAML Deserialization via Symbolication API
    cvelistv5