CVE-2026-74234
HIGHCVE-2026-74234 is a high-severity (CVSS 7.7) CWE-95 vulnerability. O3 Security confirms whether CVE-2026-74234 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Legora before 2026-08-14 contains a cross-site scripting vulnerability that allows attackers to achieve arbitrary JavaScript execution in a victim's browser by embedding a Mermaid block…
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-74234.
Description
Legora before 2026-08-14 contains a cross-site scripting vulnerability that allows attackers to achieve arbitrary JavaScript execution in a victim's browser by embedding a Mermaid block prefixed with a gray-matter JavaScript front-matter directive, causing the front-matter parser to invoke eval() before any SVG sanitization occurs. Attackers can exploit this flaw through influenced Mermaid diagram content to execute arbitrary JavaScript in the user's browser context, with elevated impact on Word and Outlook add-in surfaces where bearer session tokens are persisted in localStorage.
Detection & mitigation playbook
VulnerabilityDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for the affected component. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Remediation status
No patched version of the affected component has shipped for CVE-2026-74234 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-74234 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-74234. 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-2026-74234 in your dependencies?
O3 detects CVE-2026-74234 across dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.