CVE-2026-72811 in SiYuan
Summary
by MITRE • 08/14/2026
SiYuan versions <= v3.7.2 contain a SQL injection vulnerability in the backlink/mention search query (kernel/model/backlink.go), which concatenates stored block metadata (title, name, alias, anchor text) and the client-supplied keyword into a SQL MATCH/search statement while escaping only the double-quote character and not the single quote. A single quote in the client keyword (first-order, reachable by an anonymous or RoleReader user on the publish surface) or in stored document metadata (second-order) breaks out of the string literal. Because the query runs on the main read-write siyuan.db handle via a statement-stacking-capable driver, an attacker can execute arbitrary SQL, enabling cross-notebook read and write. Fixed in v3.7.4.
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Analysis
by VulDB Data Team • 08/14/2026
The vulnerability identified in SiYuan versions prior to v3.7.4 represents a critical SQL injection flaw within the backlink and mention search functionality of the application's kernel model. This vulnerability exists specifically in the file kernel/model/backlink.go where the system constructs SQL MATCH statements for searching through stored block metadata including title, name, alias, and anchor text. The implementation demonstrates a fundamental misunderstanding of input sanitization practices by only escaping double-quote characters while leaving single quotes unescaped, creating a pathway for malicious input to manipulate the database query structure.
The technical exploitation of this vulnerability occurs through two distinct attack vectors that leverage different levels of user access and data manipulation. The first-order attack vector targets client-supplied keywords that are directly passed to the search function, making this accessible to anonymous users or those with RoleReader privileges on the publish surface. When a malicious actor inputs a keyword containing a single quote character, it breaks out of the SQL string literal context and allows arbitrary SQL command injection. The second-order attack vector becomes possible when stored document metadata contains unescaped single quotes in fields such as titles, names, aliases, or anchor text, enabling attackers to inject malicious SQL through existing content that gets processed during search operations.
The operational impact of this vulnerability extends beyond simple data extraction to enable comprehensive cross-notebook read and write capabilities. Since the vulnerable query executes against the main siyuan.db database handle using a statement-stacking-capable database driver, successful exploitation allows attackers to execute arbitrary SQL commands with full database privileges. This means that unauthorized users could potentially access, modify, or delete content across different notebooks, breaking the isolation boundaries between user data and compromising the integrity of the entire document management system. The vulnerability essentially removes all access controls within the search functionality, granting attackers elevated privileges that should only be available to authorized administrators.
The root cause of this vulnerability aligns with CWE-89 which specifically addresses SQL injection flaws in software applications. This weakness manifests as a failure to properly sanitize user-supplied input before incorporating it into database queries, demonstrating poor input validation and output encoding practices. From an adversarial perspective, this vulnerability maps directly to ATT&CK technique T1071.004 for application layer protocol manipulation, where attackers exploit database interface vulnerabilities to gain unauthorized access. The fact that this vulnerability affects the core search functionality of a note-taking application makes it particularly dangerous as it can be exploited during normal operational activities without requiring specialized attack vectors or elevated privileges.
Mitigation strategies for this vulnerability include immediate patching to version v3.7.4 which implements proper SQL escaping mechanisms, ensuring all single quotes are properly escaped or parameterized in database queries. Organizations should also implement comprehensive input validation at multiple layers including application-level sanitization and database-level parameterized queries. Regular security auditing of database interfaces and query construction practices should be conducted to identify similar vulnerabilities in other components of the system, while maintaining proper access controls and privilege separation to limit potential damage even if such vulnerabilities exist in other parts of the application architecture.