GHSA-rq77-p4h8-4crw
gorilla/csrf CSRF vulnerability due to broken Referer validation
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
github.com/gorilla/csrfReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Summary
gorilla/csrf is vulnerable to CSRF via form submission from origins that share a top level domain with the target origin.
Details
gorilla/csrf does not validate the Origin header against an allowlist. Its executes its validation of the Referer header for cross-origin requests only when it believes the request is being served over TLS. It determines this by inspecting the r.URL.Scheme value. However, this value is never populated for "server" requests per the Go spec, and so this check does not run in practice.
// URL specifies either the URI being requested (for server
// requests) or the URL to access (for client requests).
//
// For server requests, the URL is parsed from the URI
// supplied on the Request-Line as stored in RequestURI. For
// most requests, fields other than Path and RawQuery will be
// empty. (See [RFC 7230, Section 5.3](https://rfc-editor.org/rfc/rfc7230.html#section-5.3))
//
// For client requests, the URL's Host specifies the server to
// connect to, while the Request's Host field optionally
// specifies the Host header value to send in the HTTP
// request.
URL *[url](https://pkg.go.dev/net/url).[URL](https://pkg.go.dev/net/url#URL)
PoC
- create trusted origin
target.example.testprotected with gorilla/csrf and served over TLS hosting form on/submit - create attacker origin
attack.example.testserved over TLS - attacker exfiltrates token & cookie combination from
target.example.test - attacker sets exfiltrated cookie with
domain=.example.test and path=/submit- as the cookie has a more specific path than
/(the default for CSRF cookies) it will be sent first by the browser on submit to our target origin
- as the cookie has a more specific path than
- submit form from
attack.example.testwith exfiltrated CSRF form token - observe valid form submission as
attack.example.testOrigin / Referer headers are not validated.
Impact
This vulnerability allows an attacker who has gained XSS on a subdomain or top level domain to perform authenticated form submissions against gorilla/csrf protected targets that share the same top level domain.
This bug has existed in gorilla/csrf since its initial release in 2015.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/gorilla/csrf | all versions | 1.7.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/gorilla/csrf. 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 github.com/gorilla/csrf to 1.7.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-rq77-p4h8-4crw 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-rq77-p4h8-4crw 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-rq77-p4h8-4crw. 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-rq77-p4h8-4crw in your dependencies?
O3 detects GHSA-rq77-p4h8-4crw across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.