Description
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.
Scores
CVSS v3
8.1
EPSS
0.0006
EPSS Percentile
19.0%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
CISA SSVC
Vulnrichment
Exploitation
poc
Automatable
yes
Technical Impact
partial
Details
CWE
CWE-321
CWE-798
Status
published
Products (1)
b3log/siyuan
< 3.5.2
Published
Dec 27, 2025
Tracked Since
Feb 18, 2026