Vulnerability in SiYuan (CVE-2026-87808)
Summary
Vulnerability in SiYuan (CVE-2026-87808). Confidential information can be exposed externally. Exploitable via POST /api/search/fullTextSearchBlock. Mitigation: upgrade to 3.8.2 or later.
Original description
The description as published by the source.
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.
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-87808 has been found in SiYuan.
Attackers can target a specific entry point like POST /api/search/fullTextSearchBlock over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 4.9/10.
What to do: upgrade SiYuan to 3.8.2 or later.
If unsure, ask your IT team or search "SiYuan CVE-2026-87808" on the vendor's site.
CVE-2026-87808 (SiYuan) — CWE-693 / CVSS v3 4.9
Attack vector: remote (network-reachable) / no user interaction
Attack surface: POST /api/search/fullTextSearchBlock
Patched: 3.8.2 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-693) exists in SiYuan. Attackers reach the vulnerable code path via POST /api/search/fullTextSearchBlock.
Check the vendor advisory for the affected versions of SiYuan. Attack surface: POST /api/search/fullTextSearchBlock.
Severity: Medium (CVSS 4.9/10). Confidential information can be exposed externally.
Update to 3.8.2.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual POST /api/search/fullTextSearchBlock requests with malformed payloads or SQL meta-characters. Run grep -r 'SiYuan' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'SiYuan' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
SiYuanを grep し、稼働しているサービス・バージョンを把握する。 -
2Hunt for indicators of compromise detect
grep 'POST /api/search/fullTextSearchBlock' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'アクセスログで
POST /api/search/fullTextSearchBlockへの異常なリクエスト (不正な認証ヘッダ・SQLメタ文字)を過去 30〜90日分捜索。WAF/SIEM があれば該当パスのアラート発火履歴を確認。 -
3Apply patch patch
Upgrade SiYuan to 3.8.2ステージング環境で 3.8.2 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスと、Step 2 で見つけた異常検知の続報チェックを含めること。
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4Post-deployment verification verify
Replay attack against POST /api/search/fullTextSearchBlock on staging to confirm patch closes the vectorパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番では Step 2 と同じログクエリでアラート再発が無いか継続監視。
References
- web github.com
- web github.com
- web vulncheck.com
- web nvd.nist.gov
- web github.com