CVE-2026-126265siyuan-note siyuan
NVD
Vulnerability Summary
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 v4.0 Base Metrics — Score 9.1 (CRITICAL)
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:NAttack VectorNetwork
Attack ComplexityHigh
Attack RequirementsPresent
Privileges RequiredNone
User InteractionNone
Confidentiality (Vulnerable System)High
Integrity (Vulnerable System)High
Availability (Vulnerable System)None
Confidentiality (Subsequent System)None
Integrity (Subsequent System)None
Availability (Subsequent System)None
Show CVSS v3.x metrics (score 7.4)
CVSS v3.1 Base Metrics — Score 7.4 (HIGH)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:NAttack VectorNetwork
Attack ComplexityHigh
Privileges RequiredNone
User InteractionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityNone
Affected & Patched Versions
- siyuan-note siyuan >= 2.1.0 and < 3.8.9
- siyuan-note siyuan 3.8.9
What to do
Plan remediation soon. No exploitation is confirmed yet, but the severity is critical.
- Check whether you run siyuan-note siyuan and which version.
- Update to a patched version listed above, then confirm the new version.
Timeline
- Nov 13, 2026Published
- Nov 13, 2026Record last modified
Score, severity and exploitation changes are tracked from the day Watchtower started logging them.
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Data last checked: Nov 13, 2026 10:08 (site time)