CVE-2026-87808: siyuan-note siyuan Protection Mechanism Failure

Vulnerability summary

CVE-2026-87808 is a high (CVSS 8.7) Protection Mechanism Failure vulnerability in siyuan-note siyuan. EPSS estimates a 0.44% chance of exploitation in the next 30 days, higher than 37.5% of scored vulnerabilities.

Timeline

1. 09-09-2026
   PublishedVulnerability first disclosed.
2. 09-09-2026
   Last modifiedVulnerability information updated.

Description

SiYuan versions <= 3.8.1 contain an incomplete fix for CVE-2026-32767 (GHSA-j7wh-x834-p3r7). The prior fix (commit d5e2d0bc) added an administrator check for SQL mode (method=2) in POST /api/search/fullTextSearchBlock, but the endpoint still does not enforce the application's read-only boundary: for method=2 it forwards caller-supplied SQL to the blocks database query path without calling model.CheckReadonly or CheckReadonlyStatementInBox. As a result, when a workspace runs in read-only mode (--readonly=true), an authenticated administrator can submit arbitrary SQL through /api/search/fullTextSearchBlock and obtain raw read access to the blocks database, even though the dedicated /api/query/sql endpoint is blocked in that mode. Fixed in v3.8.2.

• CWE-693Protection Mechanism FailureThe product does not use or incorrectly uses a protection mechanism that provides sufficient defense against directed attacks against the product.