CVE-2026-39825

ReverseProxy forwards queries with more than urlmaxqueryparams parameters in net/http/httputil

Published May 7, 2026 CVSS 3.1 · 5.3 Medium EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

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History
Type Values Removed Values Added
Weaknesses CWE-20
Type Values Removed Values Added
First Time appeared Golang
Golang go
Weaknesses NVD-CWE-noinfo
CPEs cpe:2.3:a:golang:go:*:*:*:*:*:*:*:*
Vendors & Products Golang
Golang go
Type Values Removed Values Added
First Time appeared Go Standard Library
Go Standard Library net/http
Vendors & Products Go Standard Library
Go Standard Library net/http
Type Values Removed Values Added
Weaknesses CWE-20
Type Values Removed Values Added
Weaknesses CWE-20
Type Values Removed Values Added
Metrics cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N'}

ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Weaknesses CWE-20
Type Values Removed Values Added
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.
Title ReverseProxy forwards queries with more than urlmaxqueryparams parameters in net/http/httputil
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
Go
Published
Updated
May 8, 2026, 9:30 PM
Reserved
Apr 7, 2026, 6:13 PM
Status
Analyzed
Published
May 7, 2026, 8:16 PM
Modified
Oct 26, 2026, 8:10 PM