GHSA-q559-8m2m-g699 is a high-severity (CVSS 7.7) Information Exposure vulnerability in guzzlehttp/guzzle. A fix is available for guzzlehttp/guzzle — see the affected versions and patch details below.
Change in port should be considered a change in origin
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-q559-8m2m-g699.
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.
How urgent is this, really
GHSA-q559-8m2m-g699 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 379,145 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
guzzlehttp/guzzle🐘guzzlehttp/guzzleReal-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
Authorization and Cookie headers on requests are sensitive information. On making a request which responds with a redirect to a URI with a different port, if we choose to follow it, we should remove the Authorization and Cookie headers from the request, before containing. Previously, we would only consider a change in host or scheme downgrade. Now, we consider any change in host, port or scheme to be a change in origin.
Patches
Affected Guzzle 7 users should upgrade to Guzzle 7.4.5 as soon as possible. Affected users using any earlier series of Guzzle should upgrade to Guzzle 6.5.8 or 7.4.5.
Workarounds
An alternative approach would be to use your own redirect middleware, rather than ours, if you are unable to upgrade. If you do not require or expect redirects to be followed, one should simply disable redirects all together.
References
For more information
If you have any questions or comments about this advisory, please get in touch with us in #guzzle on the PHP HTTP Slack. Do not report additional security advisories in that public channel, however please follow our vulnerability reporting process.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | guzzlehttp/guzzle | all versions | 6.5.8composer require guzzlehttp/guzzle:^6.5.8 |
| 🐘Packagist | guzzlehttp/guzzle | ≥ 7.0.0&&< 7.4.5 | 7.4.5composer require guzzlehttp/guzzle:^7.4.5 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for guzzlehttp/guzzle, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update guzzlehttp/guzzle to 6.5.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-q559-8m2m-g699 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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-q559-8m2m-g699 can be triaged on real exposure rather than presence alone.
Tailored to GHSA-q559-8m2m-g699. 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-q559-8m2m-g699 in your dependencies?
O3 Security finds GHSA-q559-8m2m-g699 across Packagist dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.