> CVE-2026-72809 [HIGH]

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PUBLISHED
2026-08-12 20:17
MODIFIED
2026-08-12 20:17
CVSS_SCORE V3
7.1
EPSS (Prob. Exploit)
0.30%
Top 78.4%
DATA SOURCES:
NVD đź”— 2026-08-12 CWE MITRE đź”— 2026-11-01 FIRST EPSS đź”— 2026-10-25

> DESCRIPTION

SiYuan versions <= v3.7.2 (patched in v3.7.4) contain an authentication bypass vulnerability in the kernel's CheckAuth function, which grants the administrator role (RoleAdministrator) to any request whose RemoteAddr is loopback (127.0.0.1) for a specific set of endpoints (including /api/system/exit, getNetwork, getWorkspaceInfo, /assets/*, and /export/*). These localhost bypasses sit outside the access auth code gate, so they apply even when an access auth code is configured. Because the fixed-port reverse proxy forwards requests to the kernel over loopback without injecting an authentication token and does not configure trusted proxies, a request forwarded through this proxy reaches the kernel with RemoteAddr = 127.0.0.1. If the fixed-port proxy is bound to a network interface, this could allow a remote unauthenticated attacker to obtain admin access on the affected endpoints; however, per the advisory this remote forwarding behavior was established only by code inspection and was not reproduced end-to-end.

> AFFECTED_PRODUCTS

ℹ️ Aucun produit affecté n'a encore été publié par NVD pour cette CVE.

> CVSS V3 METRICS

CVSS_VECTOR
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/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

> MÉTRIQUES CVSS DÉTAILLÉES

CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/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
Métrique Valeur Interprétation
AV (Vecteur d'Attaque)
Attack Vector
Local (L)
Exploit nécessite un accès local au système
AC (Complexité d'Attaque)
Attack Complexity
Low (L)
Peu de conditions requises pour exploiter
PR (Privilèges Requis)
Privileges Required
None (N)
Aucune authentification requise
UI (Interaction Utilisateur)
User Interaction
None (N)
Aucune interaction utilisateur nécessaire
S (Périmètre)
Scope
Unchanged (U)
Impact reste dans le périmètre du composant compromis
C (Impact Confidentialité)
Confidentiality Impact
High (H)
Divulgation totale d'informations
I (Impact Intégrité)
Integrity Impact
Low (L)
Modification limitée des données possible
A (Impact Disponibilité)
Availability Impact
High (H)
Interruption totale du service possible

> RÉSUMÉ DES IMPACTS

Confidentialité
High
Divulgation totale d'informations
Intégrité
Low
Modification limitée des données possible
Disponibilité
High
Interruption totale du service possible

> WEAKNESSES

CWE-290

> CWE DETAILED DESCRIPTIONS

CWE-290: Authentication Bypass by Spoofing - This attack-focused weakness is caused by incorrectly implemented authentication schemes that are subject to spoofing attacks.

> HISTORIQUE DES MODIFICATIONS

Première apparition
12/08/2026 20:17
Source: NVD
📊 ENRICHISSEMENT 01/09/2026 06:02
CWE
Champ modifié: Description CWE
Ancienne valeur:
N/A
Nouvelle valeur:
CWE-290: Authentication Bypass by Spoofing - This attack-focused weakness is caused by incorrectly implemented authentication schemes that are subject to spoofing attacks.
Total des modifications: 1 Dernière mise à jour: 2 months ago

> REFERENCES

https://github.com/siyuan-note/siyuan/security/advisories/GHSA-3mp7-4rh5-jrv9
https://www.vulncheck.com/advisories/siyuan-before-authentication-bypass-via-loc...
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