SiYuan: Information Disclosure and Authentication Bypass via Hardcoded Session Secret

published 2025-12-27 10 mo ago modified 2026-10-13 27 d ago also EUVD-2025-205463

cvss: 8.1; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 12%
public exploits: 0; none known

SiYuan is self-hosted, open source personal knowledge management software. In versions 3.5.1 and prior, the SiYuan Note application utilizes a hardcoded cryptographic secret for its session store. This unsafe practice renders the session encryption ineffective. Since the sensitive AccessAuthCode is stored within the session cookie, an attacker who intercepts or obtains a user's encrypted session cookie (e.g., via session hijacking) can locally decrypt it using the public key. Once decrypted, the attacker can retrieve the AccessAuthCode in plain text and use it to authenticate or take over the session.

Patch / fix

fixed in 1

b3log siyuan 3.5.2

CISA SSVC

Exploitation: Proof of concept is public
Automatable: yes
Technical impact: partial
Assessed: 10 mo ago (2025-12-29)

Exploit prediction

0.22% chance of exploitation in the next 30 days, higher than 12% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/siyuan-note/siyuan/security/advisories/GHSA-f7ph-rc3w-qp28 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	4.0	6.9	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
CNA	4.0	6.9	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/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
NVD	3.1	8.1	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

siyuan-note siyuan

Classification

Weakness

CWE-321 Use of Hard-coded Cryptographic Key
CWE-798 Use of Hard-coded Credentials

References

github.com /siyuan-note/siyuan/security/advisories/GHSA-f7ph-rc3w-qp28
exploit, vendor-advisory

Sources

CVE List CVE-2025-68948
NVD CVE-2025-68948

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.

Summary