CVE-2026-39847
CRITICALCVE-2026-39847 is a critical-severity (CVSS 9.1) Path Traversal vulnerability in emmett. O3 Security confirms whether CVE-2026-39847 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Emmett has a path traversal in internal assets handler
Blast Radius
emmettReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
Emmett is a full-stack Python web framework designed with simplicity. From 2.5.0 to before 2.8.1, the RSGI static handler for Emmett's internal assets (/emmett paths) is vulnerable to path traversal attacks. An attacker can use ../ sequences (eg /emmett/../rsgi/handlers.py) to read arbitrary files outside the assets directory. This vulnerability is fixed in 2.8.1.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | emmett | ≥ 2.5.0&&< 2.8.1 | 2.8.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for emmett. 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.
Fix
Update emmett to 2.8.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-39847 is resolved across your whole dependency graph.
Workarounds
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-2026-39847 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-2026-39847. 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-2026-39847 in your dependencies?
O3 detects CVE-2026-39847 across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.