CVE-2026-39825
ReverseProxy forwards queries with more than urlmaxqueryparams parameters in net/http/httputil
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.
INFO
Published Date :
May 7, 2026, 8:16 p.m.
Last Modified :
May 13, 2026, 4:58 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | MEDIUM | 134c704f-9b21-4f2e-91b3-4a467353bcc0 |
Solution
- Update the Go version to a patched release.
- Configure GODEBUG=urlmaxqueryparams=N if applicable.
- Review ReverseProxy and Rewrite function configurations.
Public PoC/Exploit Available at Github
CVE-2026-39825 has a 1 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-39825.
| URL | Resource |
|---|---|
| https://go.dev/cl/770541 | Patch |
| https://go.dev/issue/78948 | Issue Tracking |
| https://groups.google.com/g/golang-announce/c/qcCIEXso47M | Release Notes |
| https://pkg.go.dev/vuln/GO-2026-4976 | Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-39825 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-39825
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
This project provides a simple example of Spring Boot CRUD application with Postgres DB, docker-compose and LGTM Observability support
docker docker-compose grafana jdbc lgtm-stack makefile postgres spring-boot
Makefile Shell Dockerfile Java
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-39825 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-39825 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
May. 13, 2026
Action Type Old Value New Value Added CWE NVD-CWE-noinfo Added CPE Configuration OR *cpe:2.3:a:golang:go:*:*:*:*:*:*:*:* versions up to (excluding) 1.25.10 *cpe:2.3:a:golang:go:*:*:*:*:*:*:*:* versions from (including) 1.26.0 up to (excluding) 1.26.3 Added Reference Type Go Project: https://go.dev/cl/770541 Types: Patch Added Reference Type Go Project: https://go.dev/issue/78948 Types: Issue Tracking Added Reference Type Go Project: https://groups.google.com/g/golang-announce/c/qcCIEXso47M Types: Release Notes Added Reference Type Go Project: https://pkg.go.dev/vuln/GO-2026-4976 Types: Vendor Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
May. 08, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N -
New CVE Received by [email protected]
May. 07, 2026
Action Type Old Value New Value 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. Added Reference https://go.dev/cl/770541 Added Reference https://go.dev/issue/78948 Added Reference https://groups.google.com/g/golang-announce/c/qcCIEXso47M Added Reference https://pkg.go.dev/vuln/GO-2026-4976