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CVE-2026-72811 – SQL Injection / Cross-Notebook Data Exposure – SiYuan Note ≤ v3.7.2

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Summary

CVE-2026-72811 is a critical SQL injection vulnerability in SiYuan Note’s backlink/mention search functionality, affecting all versions up to and including v3.7.2. The flaw arises because stored block metadata (title, name, alias, anchor text) and client-supplied search keywords are concatenated into SQL MATCH statements with insufficient escaping, allowing attackers to break out of string literals and execute arbitrary SQL. The issue has a CVSS score of 9.9 (Critical) and can lead to unauthorized cross-notebook data disclosure and modification.

Technical details

  • Root cause: In kernel/model/backlink.go, the backlink/mention search query concatenates stored block metadata and client-supplied keywords directly into a SQL MATCH statement, escaping only double-quote characters and leaving single quotes unhandled.
  • Trigger conditions: Exploitable via two paths — (1) first-order: an anonymous reader or low-privilege user supplies a malicious keyword through the publish-mode search surface; (2) second-order: a document containing single quotes or crafted content in its title, name, alias, or anchor text is later processed by the backlink query on any kernel that has imported it.
  • Attack vector: Network, no authentication or privileges required, no user interaction — reachable through the publish-mode search API.
  • Impact: Arbitrary SQL execution against the main, read-write database handle, enabling cross-notebook data disclosure and potential unauthorized data modification.

Affected software

  • SiYuan (github.com/siyuan-note/siyuan/kernel) versions 0 through 3.7.2 (inclusive)
  • Fixed in version 3.7.4

Severity

  • CVSS v3.1 Base Score: 10.0 (Critical) — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N
  • CVSS v4.0 Base Score: 9.9 (Critical) — CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N

Mitigation and recommended actions

  • Immediate: Upgrade SiYuan to version 3.7.4 or later, where the escaping issue in the backlink/mention search query is fixed.
  • If immediate patching is not possible: Restrict or disable publish-mode exposure to untrusted networks, avoid storing untrusted or externally supplied content (titles, aliases, anchor text) in notebooks accessible via publish mode, and monitor database access logs for anomalous query patterns until the patch can be applied.

References

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