CVE-2026-100646
published 2026-09-26CVE-2026-100646: SiYuan is a self-hosted personal knowledge management system. In versions up to and including 3.8.3, the kernel's authentication guards (CheckAuth in…
PriorityP348high8.1CVSS 3.1
AVNACLPRNUIRSUCHIHAN
EPSS
0.19%
8.2th percentile
SiYuan is a self-hosted personal knowledge management system. In versions up to and including 3.8.3, the kernel's authentication guards (CheckAuth in kernel/model/session.go and IsSessionOriginAllowed in kernel/util/net.go) fail open when the HTTP Origin header is absent, on the incorrect assumption that any browser-initiated cross-site request carries an Origin. Because browsers omit Origin on cross-site top-level GET navigations and no-cors GET subresource loads — and the session cookie is SameSite=Lax — a single cross-site GET issued from any attacker-controlled web page is granted RoleAdministrator, both on default installations with no access-authorization code and on password-protected instances with a live session. Combined with content-type sniffing on the /api/network/proxy endpoint, which allows attacker-controlled HTML to be served under SiYuan's own origin, this permits an unauthenticated remote attacker to execute arbitrary script in the SiYuan origin (http://127.0.0.1:6806), invoke administrator APIs, and exfiltrate the persistent kernel API token. This issue is fixed in version 3.8.4.
Affected
1 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| siyuan-note | siyuan | < 3.8.4 | 3.8.4 |
CVSS provenance
nvdv3.18.1HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
nvdv4.08.6HIGHCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
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GHSA
SiYuan is a self-hosted personal knowledge management system.
ghsa_unreviewed·2026-09-26
CVE-2026-100646 [HIGH] CWE-346 SiYuan is a self-hosted personal knowledge management system.
SiYuan is a self-hosted personal knowledge management system. In versions up to and including 3.8.3, the kernel's authentication guards (CheckAuth in kernel/model/session.go and IsSessionOriginAllowed in kernel/util/net.go) fail open when the HTTP Origin header is absent, on the incorrect assumption that any browser-initiated cross-site request carries an Origin. Because browsers omit Origin on cross-site top-level GET navigations and no-cors GET subresource loads — and the session cookie is SameSite=Lax — a single cross-site GET issued from any attacker-controlled web page is granted RoleAdministrator, both on default installations with no access-authorization code and on password-protected instances with a live session. Combined with content-type sniffing on the /api/network/proxy endpoi
VulDB
SiYuan Note up to 3.8.3 Session Origin Validation kernel/model/session.go CheckAuth improper authorization
vuldb·2026-09-26·CVSS 8.1
CVE-2026-100646 [HIGH] SiYuan Note up to 3.8.3 Session Origin Validation kernel/model/session.go CheckAuth improper authorization
A vulnerability labeled as critical has been found in SiYuan Note SiYuan up to 3.8.3. This impacts the function CheckAuth of the file kernel/model/session.go of the component Session Origin Validation. Such manipulation of the argument Origin leads to improper authorization.
This vulnerability is uniquely identified as CVE-2026-100646. The attack can be launched remotely. No exploit exists.
The affected component should be upgraded.
No detection rules found.
No public exploits indexed.
No writeups or analysis indexed.
2026-09-26
Published