CVE-2021-3907
CRITICALCVE-2021-3907 is a critical-severity (CVSS 9.8) Improper Input Validation vulnerability in github.com/cloudflare/cfrpki. O3 Security confirms whether CVE-2021-3907 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Path traversal in github.com/cloudflare/cfrpki/cmd/octorpki
Blast Radius
github.com/cloudflare/cfrpkiReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
OctoRPKI does not escape a URI with a filename containing "..", this allows a repository to create a file, (ex. rsync://example.org/repo/../../etc/cron.daily/evil.roa), which would then be written to disk outside the base cache folder. This could allow for remote code execution on the host machine OctoRPKI is running on.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/cloudflare/cfrpki | all versions | 1.4.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/cloudflare/cfrpki. 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 github.com/cloudflare/cfrpki to 1.4.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-3907 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-2021-3907 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-2021-3907. 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-2021-3907 in your dependencies?
O3 detects CVE-2021-3907 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.