GHSA-q2qj-628g-vhfw is a medium-severity (CVSS 6.5) CWE-436 vulnerability in slim/psr7. 1 public exploit reference exists, so weaponization risk is real. O3 Security confirms whether GHSA-q2qj-628g-vhfw is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Insecure header validation in slim/psr7
Real-World Exposure
slim/psr7🐘slim/psr7🐘slim/psr7Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
Impact
An attacker could sneak in a newline (\n) into both the header names and values. While the specification states that \r\n\r\n is used to terminate the header list, many servers in the wild will also accept \n\n. An attacker that is able to control the header names that are passed to Slilm-Psr7 would be able to intentionally craft invalid messages, possibly causing application errors or invalid HTTP requests being sent out with an PSR-18 HTTP client. The latter might present a denial of service vector if a remote service’s web application firewall bans the application due to the receipt of malformed requests.
Patches
The issue is patched in 1.6.1, 1.5.1, and 1.4.1.
Workarounds
In Slim-Psr7 prior to 1.6.1, 1.5.1, and 1.4.1, validate HTTP header keys and/or values, and if using user-supplied values, filter them to strip off leading or trailing newline characters before calling withHeader().
Acknowledgments
We are very grateful to and thank <a href="https://gjcampbell.co.uk/">Graham Campbell</a> for reporting and working with us on this issue.
References
- Guzzle: CVE-2023-29197, with advisory GHSA-wxmh-65f7-jcvw
- Laminas Diactoros: CVE-2023-29530, with advisory GHSA-xv3h-4844-9h36
- https://www.rfc-editor.org/rfc/rfc7230#section-3.2.4
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | slim/psr7 | ≥ 1.6&&< 1.6.1 | 1.6.1 |
| 🐘Packagist | slim/psr7 | ≥ 1.5&&< 1.5.1 | 1.5.1 |
| 🐘Packagist | slim/psr7 | all versions | 1.4.1 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for slim/psr7. 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 slim/psr7 to 1.6.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-q2qj-628g-vhfw 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-q2qj-628g-vhfw 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-q2qj-628g-vhfw. 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-q2qj-628g-vhfw in your dependencies?
O3 detects GHSA-q2qj-628g-vhfw across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.