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CVE-2026-74902

8.6 · HIGH

SiYuan before v3.7.4 contains a cross-site scripting vulnerability in the file upload validation flow that fails to escape filenames before inserting them into HTML via insertAdjacentHTML.

Published Aug 18, 2026CWE-79EPSS 0.20%

Overview

CVE-2026-74902 is a high-severity vulnerability. It was published on August 18, 2026 and has a CVSS 3.1 base score of 8.6 (HIGH).

This vulnerability has a CVSS 3.1 base score of 8.6, rated HIGH. It requires local or adjacent network access to exploit. No authentication or special privileges are required for exploitation.

Technical description

SiYuan before v3.7.4 contains a cross-site scripting vulnerability in the file upload validation flow that fails to escape filenames before inserting them into HTML via insertAdjacentHTML. Attackers can craft a malicious filename containing script payloads that execute with full OS command access when a user drags, drops, or pastes the file into the editor.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/siyuan-note/siyuan/security/advisories/GHSA-jf56-jrhq-j2qpRefwww.vulncheck.com/advisories/siyuan-before-xss-to-rce-via-malicious-filename-upload

How CyberStrike helps

Frequently asked questions

What is CVE-2026-74902?

CVE-2026-74902 is a high-severity vulnerability. It was published on August 18, 2026 and has a CVSS 3.1 base score of 8.6 (HIGH).

How severe is CVE-2026-74902?

This vulnerability has a CVSS 3.1 base score of 8.6, rated HIGH. It requires local or adjacent network access to exploit. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-74902?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-74902?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-74902 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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