GHSA-8274-h5jp-97vr is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in laminas/laminas-diactoros. A fix is available for laminas/laminas-diactoros — see the affected versions and patch details below.
Diactoros before 2.11.1 vulnerable to HTTP Host Header Attack
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- 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-8274-h5jp-97vr.
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-8274-h5jp-97vr 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 377,333 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
laminas/laminas-diactorosReal-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
Applications that use Diactoros, and are either not behind a proxy, or can be accessed via untrusted proxies, can potentially have the host, protocol, and/or port of a Laminas\Diactoros\Uri instance associated with the incoming server request modified to reflect values from X-Forwarded-* headers. Such changes can potentially lead to XSS attacks (if a fully-qualified URL is used in links) and/or URL poisoning.
Patches
Any version after 2.11.0.
Starting in laminas/laminas-diactoros 2.11.1, we have added Laminas\Diactoros\ServerRequestFilter\FilterServerRequestInterface, which defines the single method __invoke(Psr\Http\Message\ServerRequestInterface $request): Psr\Http\Message\ServerRequestInterface. Filters implementing this interface allow modifying and returning a generated ServerRequest.
The primary use case of the interface is to allow modifying the generated URI based on the presence of headers such as X-Forwarded-Host. When operating behind a reverse proxy, the Host header is often rewritten to the name of the node to which the request is being forwarded, and an X-Forwarded-Host header is generated with the original Host value to allow the server to determine the original host the request was intended for. (We have always examined the X-Forwarded-Proto header; as of Diactoros 2.11.1, we also examine the X-Forwarded-Port header.) To accommodate this use case, we created Laminas\Diactoros\ServerRequestFilter\FilterUsingXForwardedHeaders.
Due to potential security issues, it is generally best to only accept these headers if you trust the reverse proxy that has initiated the request.
(This value is found in $_SERVER['REMOTE_ADDR'], which is present as $request->getServerParams()['REMOTE_ADDR'] within PSR-7 implementations.) FilterUsingXForwardedHeaders provides named constructors to allow you to trust these headers from any source (which has been the default behavior of Diactoros since the beginning), or to specify specific IP addresses or CIDR subnets to trust, along with which headers are trusted.
Laminas\Diactoros\ServerRequestFactory::fromGlobals() was updated to accept a FilterServerRequestInterface as an additional, optional argument. Since the X-Forwarded-* headers do have valid use cases, particularly in clustered environments using a load balancer, to prevent backwards compatibility breaks, if no filter is provided, we generate an instance via FilterUsingXForwardedHeaders::trustReservedSubnets(), which generates an instance marked to trust only proxies on private subnets.
Workarounds
Infrastructure or DevOps can configure web servers to reject X-Forwarded-* headers at the web server level.
Users of laminas/laminas-diactoros can make use of the Laminas\Diactoros\RequestFilter\RequestFilterInterface functionality in order to either (a) disable usage of the X-Forwarded-* headers entirely, (b) opt-in to it, or (c) opt-in to the usage for configured proxy servers.
References
For more information
If you have any questions or comments about this advisory:
- Open an issue in laminas/laminas-diactoros
- Email us
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | laminas/laminas-diactoros | all versions | 2.11.1composer require laminas/laminas-diactoros:^2.11.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for laminas/laminas-diactoros, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update laminas/laminas-diactoros to 2.11.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-8274-h5jp-97vr 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-8274-h5jp-97vr can be triaged on real exposure rather than presence alone.
Tailored to GHSA-8274-h5jp-97vr. 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-8274-h5jp-97vr in your dependencies?
O3 Security finds GHSA-8274-h5jp-97vr across Packagist dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.