CVE-2026-116167: SiYuan 2.9.0 before 3.8.7 XSS via check-auth to Parameter
Advisory generated from the CVE record, CISA, Exploit Observer and VEDAS: what it is, whether it is exploited, who is affected, and how to fix and detect it.
Generated by VEDAS. Scores as of 2026-11-04 15:41 UTC. Rebuilt every few hours from cve-scores, CISA KEV and vedas-signatures. How this works and its limits.
What it is
SiYuan from 2.9.0 before 3.8.7 contains a cross-site scripting vulnerability in the unauthenticated /check-auth page that assigns the to parameter to window.location.href without scheme validation. Attackers can send a crafted link with a javascript: URI that executes after victim login, invoking kernel APIs to read or modify workspace content and settings.
Description quoted from the CVE record (assigned by VulnCheck, published 2026-10-25).
Weakness: Improper Neutralization of Input During Web Page Generation (‘Cross-site Scripting’)
How it can be exploited
Exploitable over the network with high attack complexity only when specific conditions are present needing no privileges and a user must take an action. Impact: confidentiality high, integrity high, availability none. CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
CISA assessment (SSVC): CISA has no evidence of exploitation. Automatable: no. Technical impact: total.
Public exploit evidence (Exploit Observer)
Exploit Observer found 1 Nuclei template naming this CVE.
See all 3 references on Exploit Observer
Live scores
- EPSS
- 0.007
low predicted chance of attack - VEDAS
- 0.986
strong exploit evidence - On CISA KEV
- Not listed
- Detection rule
- No public rule yet
Who is affected
| Product | Affected | Not affected |
|---|---|---|
| siyuan-note siyuan | from 2.9.0 before 3.8.7 | 3.8.7 is not affected |
Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.
How to fix it
Fixed versions stated in the CVE record: 3.8.7.
Vendor guidance:
- GitHub Security Advisory (GHSA-fmj3-xc2f-6w4w) (vendor-advisory)
How to detect it
There is no open VEDAS detection rule for this bug yet. It is listed on the detection gaps page if CISA has confirmed attacks.
References
Vendor advisories and patches
- GitHub Security Advisory (GHSA-fmj3-xc2f-6w4w) (vendor-advisory)
Technical analysis and advisories
- VulnCheck Advisory: SiYuan 2.9.0 before 3.8.7 XSS via check-auth to Parameter (third-party-advisory)
Other databases
Where this comes from
This advisory is generated automatically by VEDAS from: CVE.org record, cve-scores (EPSS and VEDAS), Exploit Observer. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.
Supporting partners
