CVE-2026-100636 — Siyuan-note
HIGHCVE-2026-100636 is a high-severity (CVSS 7.6) Path Traversal vulnerability. No vendor fix is recorded yet; mitigation options are listed below.
SiYuan versions before v3.8.4 contain a path traversal vulnerability in the exportBrowserHTML endpoint that allows authenticated administrators to write arbitrary HTML content to index.html…
Description
SiYuan versions before v3.8.4 contain a path traversal vulnerability in the exportBrowserHTML endpoint that allows authenticated administrators to write arbitrary HTML content to index.html outside the workspace directory. Attackers can supply a folder parameter with directory traversal sequences to escape the export directory and overwrite index.html in any pre-existing kernel-writable location, enabling stored XSS or workspace defacement.
Detection & mitigation playbook
VulnerabilityDetect
Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`). Because exploitation targets the running service rather than your application code, O3 also flags the exploit behaviour from runtime telemetry and egress traffic.
Remediation status
No fixed release is recorded for CVE-2026-100636 yet. Track the upstream advisory, and apply the exposure-reduction steps below in the meantime.
Mitigate without a patch
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page. O3's runtime protection blocks the path traversal flaw at execution, which holds the line on hosts you cannot patch immediately.
How O3 protects you
O3 detects and blocks CVE-2026-100636 exploitation at runtime with eBPF exploit-chain detection, plus L7 egress monitoring that catches a post-exploitation callback and cuts the attacker's outbound channel.
Tailored to CVE-2026-100636. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-100636 in your dependencies?
O3 Security finds CVE-2026-100636 across dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.