Vulnerability Description
ReverseProxy can forward queries containing parameters not visible to Rewrite functions. When used with a Rewrite function, or a Director function which parses query parameters, ReverseProxy sanitizes the forwarded request to remove query parameters which are not parsed by url.ParseQuery. ReverseProxy does not take ParseQuery's limit on the total number of query parameters (controlled by GODEBUG=urlmaxqueryparams=N) into account. This can permit ReverseProxy to forward a request containing a query parameter that is not visible to the Rewrite function. For example, the query "a1=x&a2=x&...&a10000=x&hidden=y" can forward the parameter "hidden=y" while hiding it from the proxy's Rewrite function.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Golang | Go | < 1.25.10 |
References
- https://go.dev/cl/770541Patch
- https://go.dev/issue/78948Issue Tracking
- https://groups.google.com/g/golang-announce/c/qcCIEXso47MRelease Notes
- https://pkg.go.dev/vuln/GO-2026-4976Vendor Advisory
FAQ
What is CVE-2026-39825?
CVE-2026-39825 is a vulnerability with a CVSS score of 5.3 (MEDIUM). ReverseProxy can forward queries containing parameters not visible to Rewrite functions. When used with a Rewrite function, or a Director function which parses query parameters, ReverseProxy sanitizes...
How severe is CVE-2026-39825?
CVE-2026-39825 has been rated MEDIUM with a CVSS base score of 5.3/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-39825?
Check the references section above for vendor advisories and patch information. Affected products include: Golang Go.