GHSA-f5p7-9fr5-8jmj
MEDIUMGHSA-f5p7-9fr5-8jmj is a medium-severity (CVSS 5.9) CWE-248 vulnerability in granian. O3 Security confirms whether GHSA-f5p7-9fr5-8jmj is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Granian vulnerable to DoS via WSGI response header panic
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
granianReal-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
Summary
Granian aborts a worker process if a WSGI application returns an invalid HTTP response header name or value. The WSGI response conversion path uses .unwrap() on both the header name and header value constructors, so malformed output from the application becomes a process abort instead of a handled error.
This issue requires a buggy or attacker-influenced WSGI application to emit invalid headers. It is not a parser bug in Granian's request path. The security impact is that application mistakes which should result in a 500 instead kill the worker process.
Details
If either conversion fails, .unwrap() panics. In release builds Granian uses panic = "abort", so the panic terminates the worker.
Preconditions
The attacker must be able to influence a header name or value produced by the WSGI application, or the application must otherwise generate invalid headers.
Examples include:
- a header name containing a space
- a header value containing
\r\n - a header value containing a null byte
These are realistic failure modes for applications that reflect user-controlled data into headers such as Location, Content Disposition, or custom response headers.
PoC
Step 1
start Granian with the PoC WSGI app
# app.py
def app(environ, start_response):
path = environ.get("PATH_INFO", "/")
if path == "/crash-name":
headers = [("X Bad Name", "value")]
elif path == "/crash-value":
headers = [("Content-Type", "text/html\r\nX-Injected: evil")]
elif path == "/crash-null":
headers = [("X-Custom", "value\x00end")]
else:
start_response("200 OK", [("Content-Type", "text/plain")])
return [b"OK - server alive\n"]
start_response("200 OK", headers)
return [b"This response kills the worker\n"]
granian --interface wsgi app:app --host 127.0.0.1 --port 8000
Step 2
trigger the crash (any one of these is sufficient)
curl http://127.0.0.1:8000/crash-name
curl http://127.0.0.1:8000/crash-value
curl http://127.0.0.1:8000/crash-null
Expected result:
- the worker aborts after any of the crash paths
- subsequent requests fail until the worker is restarted
Impact
- Worker process denial of service
- A single bad response kills one worker
- Application bugs become process crashes instead of request-scoped failures
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | granian | ≥ 0.2.0&&< 2.7.4 | 2.7.4 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for granian. 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 granian to 2.7.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-f5p7-9fr5-8jmj 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-f5p7-9fr5-8jmj 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-f5p7-9fr5-8jmj. 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-f5p7-9fr5-8jmj in your dependencies?
O3 detects GHSA-f5p7-9fr5-8jmj across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.