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14 results

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CVE-2026-72809

SiYuan before v3.7.4 Authentication Bypass via Localhost Trust

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.

Public exploit

An exploit or proof of concept is public: anyone can try it against an unpatched system. A reference of the record is tagged as an exploit. CISA's SSVC rates its exploitation: a proof of concept is public.

Show the exploits1

References tagged exploit1 reference

Timeline

  1. ID reserved

    By VulnCheck

  2. · 2 days later

    Published

  3. · 2 days later

    Record updated

Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.

Scores

CVSS scores of CVE-2026-72809, by who scored it
Scored byCVSSScoreVector
VulnCheckCNA (assigner)4.0High7.1CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:H/SC:N/SI:N/SA:N
VulnCheckCNA (assigner)3.1High8.0CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:H
NVDNVD · Deferred4.0High7.1CVSS: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
EPSS (exploitation in 30 days)
0.30% · top 77% of all CVEs (11 Nov 2026)
CISA SSVC
Exploitation: poc · Automatable: no · Technical impact: partial
Loading the EPSS history…

The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.1.

Affected products

Affected packages

From reviewed advisories of the GitHub Advisory Database.

References

References2

Sources

The same CVE in the primary databases and aggregators, to check against.

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Record last updated .