EUVD Vulnerability Catalog

EUVD-2026-125256

Severity: CRITICAL Base Score: 9.1 CVSS Version: 4.0

Vulnerability Description

SiYuan 2.1.0 before 3.8.9 contains a flaw where the loginAuth CAPTCHA challenge lives in a signed client-side cookie, allowing reuse of a solved challenge. Attackers can replay the original signed siyuan cookie with distinct wrong access codes to brute-force the code and gain an administrator session.

CVSS Vector Analysis

Below is the complete, human-readable breakdown of the CVSS metric string: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

▪ Attack Vector (AV): Network

▪ Attack Complexity (AC): High

▪ Attack Requirements (AT): Present

▪ Privileges Required (PR): None

▪ User Interaction (UI): None

▪ Vulnerability Confidentiality Impact (VC): High

▪ Vulnerability Integrity Impact (VI): High

▪ Vulnerability Availability Impact (VA): None

▪ Subsequent Confidentiality Impact (SC): None

▪ Subsequent Integrity Impact (SI): None

▪ Subsequent Availability Impact (SA): None

Affected Vendors & Systems

Vendor siyuan-note

References & Advisory Links

Metadata Profile

Database Authority

European Union Agency for Cybersecurity (ENISA) EUVD

Assigner

VulnCheck

EPSS Probability

Known Aliases

CVE-2026-126265

Published On

2026-11-13

Last Updated

2026-11-13