CVE-2026-39825

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

Published: May 7, 2026Updated: May 13, 2026 Sources: CVE List NVD BDUNVD-CWE-noinfo

5.3MEDIUM

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.

No summary for this CVE yet.

CVSS Vector Breakdown

Exploitability

AV:NAttack Vector

Network

AC:LAttack Complexity

Low

PR:NPrivileges Required

None

UI:NUser Interaction

None

Scope

S:UScope

Unchanged

Impact

C:LConfidentiality

Low

I:NIntegrity

None

A:NAvailability

None

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Weaknesses

NVD-CWE-noinfo

Affected Products

golang

oss-project·US

OSS Libraries

Go standard library

oss-project·USaka crypto/x509, net/http, html/template, golang standard library

net/http/httputilLibraryLibrary

OSS Libraries / generic-library

The Go Project

oss-projectaka go, golang-google-protobuf, crypto

OSS Libraries

Exploitability

Official Patch Available

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References

https://go.dev/cl/770541

go.dev

https://go.dev/issue/78948

go.dev

https://groups.google.com/g/golang-announce/c/qcCIEXso47M

groups.google.com

and 1 more references View all →

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