CVE-2026-109391

CRITICAL
INFO Priority: 0.04 BB Relevance: 68/100
Published: 2026-10-12 Modified: 2026-10-27 First seen: 2026-10-29 Status: active

Attack Surface

Network No Auth No Interaction Conf. Impact Integ. Impact

CVSS Vector Breakdown

AV: Network
AC: High
PR: None
UI: None
AT: Present
VC: High
VI: High
VA: High

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.

Weakness Classification (1)

Bug Bounty Relevance

68 / 100
✓ Network accessible
✓ No authentication
✓ No user interaction

CVSS Score

9.2 / 10.0 v4.0
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 — Exploitation Probability

0.48%
Raw Score 0.004770
Percentile 41.1%
Date 2026-10-29

EPSS Trend

2026-10-29
0.00477
2026-10-28
0.00477

Intelligence Sources

mitre ref →