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VulnerabilityPublished Updated

CVE-2026-100633: siyuan · Incorrect Authorization

Affects siyuanSource CVE Database V5

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Not known to be exploited · CVSS 8.5 High : upgrade to 3.8.4 soon.

Data as of 9 Nov 2026, 23:24 UTC

CVSS 4.0 base score
8.5High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.4% chance of exploitation in 30 days – higher than 34% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 3.8.4
CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 26 Sep 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: evidence found.

    Public exploit code: GitHub proofs of concept

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), GitHub proofs of concept, the Metasploit, Exploit-DB and nuclei-templates index as of 10 Nov 2026.

What to do

Upgrade siyuan and siyuan-note/siyuan to 3.8.4.

Affected software

ProductAffectedFixed in
siyuan-notesiyuanAffected
  • >=3.8.0 <3.8.4
Fixed in
  • 3.8.4
GitHubsiyuan-note/siyuanpkg:github/siyuan-note/siyuanOther threatsAffected
  • >=3.8.0 <3.8.4
Fixed in
  • 3.8.4

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade SiYuan to version 3.8.4 or later, where this vulnerability is fixed. If you cannot patch yet, restrict administrator access to trusted users only and avoid using the in-app Agent or external MCP server for recursive file operations on sensitive paths. No other vendor advisories indicate alternative mitigations or that the issue is already mitigated.

Description

SiYuan versions 3.8.0 through 3.8.3 contain an authorization bypass vulnerability in the MCP file tool's sensitive-path guard. The guard is applied only to the root of recursive operations but not to each descendant path, allowing an authenticated administrator to bypass protections on sensitive files and directories. This enables actions such as reading, copying, and overwriting protected files without proper confirmation. The issue is fixed in version 3.8.4.

References

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