CVE-2026-126265
SiYuan 2.1.0 before 3.8.9 CAPTCHA Bypass via Stale Login Cookie
Published Nov 13, 2026
CVSS 4.0 · 9.1 Critical
EPSS n/a
KEV · Not listed
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.
Analysis
Affected Products
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CVE record
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NVD configurations
No data
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Red Hat packages
No data
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OpenCVE enrichment
No data
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| siyuan-note | siyuan | unaffected |
|
No data.
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No data available yet.
Remediation
Tracking
Advisories
Metrics
Attack Vector Network
Attack Complexity High
Privileges Required None
Attack Requirements Present
User Interaction None
Vulnerable System Confidentiality Impact High
Vulnerable System Integrity Impact High
Vulnerable System Availability Impact None
Subsequent System Confidentiality Impact None
Subsequent System Integrity Impact None
Subsequent System Availability Impact None
Attack Vector Network
Attack Complexity High
Privileges Required None
Scope Unchanged
Confidentiality Impact High
Integrity Impact High
Availability Impact None
User Interaction None
No CVSS v3.0
No CVSS v2
This CVE is not in the KEV list.
No EPSS score available.
Key SSVC decision points have not yet been added.
References
History
Nov 13, 2026 9:45 AM
Description updated. Title updated. First appearance in the feed. Weaknesses updated. Affected versions updated. Affected vendors updated. Added references. Scoring metrics updated
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| Title | SiYuan 2.1.0 before 3.8.9 CAPTCHA Bypass via Stale Login Cookie | |
| First Time appeared |
B3log
B3log siyuan |
|
| Weaknesses | CWE-307 | |
| CPEs | cpe:2.3:a:b3log:siyuan:*:*:*:*:*:*:*:* | |
| Vendors & Products |
B3log
B3log siyuan |
|
| References |
| |
| Metrics |
cvssV3_1
|
Weaknesses
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CWE-307
Improper Restriction of Excessive Authentication Attempts
Sources
Vulnrichment
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NVD
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Red Hat
No data
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OpenCVE enrichment
No data
No data.