GHSA-crq5-92j2-j7wv is a medium-severity (CVSS 5.9) Path Traversal vulnerability in org.http4s:http4s-server_2.12. O3 Security confirms whether GHSA-crq5-92j2-j7wv is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Http4s: ResourceService and Webjar Service path escape via percent-encoded separators
Exploitation Status
No confirmed exploitation observed yet
- 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 GHSA-crq5-92j2-j7wv.
Real-World Exposure
org.http4s:http4s-server_2.12☕org.http4s:http4s-server_2.13☕org.http4s:http4s-server_3☕org.http4s:http4s-server_3☕org.http4s:http4s-server_2.13Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
The static content handlers ResourceService and WebjarService URL decode each path segment and then reject only segments that are exactly "", ".", or "..". A percent-encoded separator (%2F) lets an attacker smuggle a ../ segment past that filter and escape the configured base, reading resources that should not be public.
On Windows, a similar attack exists with (%5C).
Impact
Disclosure of classpath or webjar resources outside the configured base.
Preconditions
- Application uses
ResourceService(with a non-root base path) orWebjarService - At least one classpath entry is served from a directory (e.g.
sbt run, exploded .war) - Backend forwards
%2F/%5Cwithout normalizing (e.g., Ember, Blaze)
Fixes
The patch rejects any decoded path segment containing / (%2F) or \ (%5C) with a 400 Bad Request in ResourceService and WebjarService.
FileService was not exploitable, but the same guards are applied for consistency and to remove its reliance on path normalization.
Workarounds
- Deploy as a fat jar, with no filesystem directories on the classpath.
- Front the service with a proxy that rejects/normalizes
%2Fand%5Cin the request path.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.http4s:http4s-server_2.12 | all versions | 0.23.35 |
| ☕Maven | org.http4s:http4s-server_2.13 | all versions | 0.23.35 |
| ☕Maven | org.http4s:http4s-server_3 | all versions | 0.23.35 |
| ☕Maven | org.http4s:http4s-server_3 | ≥ 1.0.0-M1&&< 1.0.0-M47 | 1.0.0-M47 |
| ☕Maven | org.http4s:http4s-server_2.13 | ≥ 1.0.0-M1&&< 1.0.0-M47 | 1.0.0-M47 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.http4s:http4s-server_2.12. 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 org.http4s:http4s-server_2.12 to 0.23.35 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-crq5-92j2-j7wv 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 GHSA-crq5-92j2-j7wv 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 GHSA-crq5-92j2-j7wv. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-crq5-92j2-j7wv in your dependencies?
O3 detects GHSA-crq5-92j2-j7wv across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.