Description

SiYuan versions before v3.7.4 fail to validate that packageName matches the downloaded package content in bazaar install endpoints. Attackers with same-origin access can overwrite existing trusted plugins by supplying mismatched packageName and repoURL parameters, achieving persistence across application restarts.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "6.6",
  "pubDate": "2026-08-22T13:16:39.547Z",
  "pubdate": "2026-08-22T13:16:39.547Z",
  "executiveSummary": "A package validation flaw exists in SiYuan versions before v3.7.4 within the bazaar install endpoints, classified as an integrity validation bypass leading to arbitrary file overwrite and persistent code execution. The vulnerability impacts SiYuan installations by allowing unauthorized modification of trusted plugin directories through mismatched parameter inputs. Risk implications include the compromise of application integrity, unauthorized execution of arbitrary code within the context of the application, and the establishment of persistence mechanisms that survive application restarts. Attack capabilities require same-origin access to the application instance, enabling malicious actors to manipulate the installation workflow. Exploitation prerequisites mandate that the attacker has established same-origin access to target endpoints and can supply arbitrary or mismatched packageName and repoURL parameters during the bazaar installation process, thereby bypassing internal trust boundaries.",
  "technicalDetails": "The vulnerability stems from insufficient input validation and cryptographic or logical verification within the bazaar install endpoints of SiYuan. Specifically, the affected component fails to enforce a strict validation check to ensure that the user-supplied packageName parameter cryptographically or structurally matches the actual content retrieved from the specified repoURL. Affected versions include all instances of SiYuan prior to v3.7.4. The vulnerability can be exploited by an attacker who possesses same-origin access to the application environment, requiring no higher-level administrative privileges beyond the capability to interact with the bazaar installation interface.\nThe attack flow proceeds as follows: First, the attacker initiates a plugin installation request via the bazaar install endpoint. Instead of supplying matching parameters, the attacker crafts a malicious request where the packageName parameter corresponds to an existing, trusted, and installed plugin, while the repoURL parameter points to a malicious repository or package controlled by the attacker containing arbitrary payload behavior. Because the application fails to validate whether the package content aligns with the declared packageName, it processes the download and extracts the untrusted package content directly into the directory path associated with the trusted plugin. This results in the systematic overwriting of existing trusted plugin files with malicious code.\nThe post-exploitation impact is severe, as the overwritten plugins are loaded and executed during normal application operations or upon subsequent initialization cycles. This achieves code execution persistence across application restarts, allowing the attacker to maintain continuous unauthorized access, intercept sensitive user data, or execute arbitrary operations within the security context of the SiYuan process."
}