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VulnerabilityPublished Updated

CVE-2026-100635: siyuan · Cleartext Transmission

Affects siyuanSource CVE Database V5

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Not known to be exploited · CVSS 8.2 High : upgrade to 3.8.4 soon.

Data as of 8 Nov 2026, 23:24 UTC

CVSS 4.0 base score
8.2High
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (VulnCheck)CVSS 4.08.2
CNA (VulnCheck)CVSS 3.15.9
EPSS
0.3% chance of exploitation in 30 days – higher than 25% 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:P/PR:N/UI:N/VC:H/VI:N/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: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  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), the Metasploit, Exploit-DB and nuclei-templates index as of 9 Nov 2026.

What to do

Upgrade siyuan and siyuan-note/siyuan to 3.8.4.

Affected software

ProductAffectedFixed in
siyuan-notesiyuanAffected
  • <3.8.4
Fixed in
  • 3.8.4
GitHubsiyuan-note/siyuanpkg:github/siyuan-note/siyuanOther threatsAffected
  • <3.8.4
Fixed in
  • 3.8.4
Gosiyuanpkg:golang/siyuanOther threatsAffected
  • <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. The fix addresses the insecure transmission of session cookies by enforcing Secure and SameSite attributes and presumably using encrypted connections. No other mitigation is indicated.

Description

SiYuan versions prior to 3.8.4 have an authentication bypass vulnerability in the publish service. Session cookies are transmitted without Secure or SameSite attributes over plaintext HTTP, allowing an attacker on the network path to capture and replay a valid session cookie to access authenticated publish endpoints without the account password. This issue is fixed in version 3.8.4.

References

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