Vulnerability · Published May 7, 2026 · Assigned by Go
CVE-2026-39825ReverseProxy forwards queries with more than urlmaxqueryparams parameters in net/http/httputil
Medium 5.3
In plain English
A medium-severity security flaw in net/http/httputil from Go standard library. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 33% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux:8 | delve | 1.25.2-1.module_el8.10.0+4074+24330916 | ALSA-2026:22112 |
| AlmaLinux:8 | go-toolset | 1.25.10-1.module_el8.10.0+4187+c45165c4 | ALSA-2026:22112 |
| AlmaLinux:9 | go-toolset | 1.26.3-1.el9_8 | ALSA-2026:22121 |
| AlmaLinux:8 | golang | 1.25.10-1.module_el8.10.0+4187+c45165c4 | ALSA-2026:22112 |
| AlmaLinux:9 | golang | 1.26.3-1.el9_8 | ALSA-2026:22121 |
| AlmaLinux:8 | golang-bin | 1.25.10-1.module_el8.10.0+4187+c45165c4 | ALSA-2026:22112 |
| AlmaLinux:9 | golang-bin | 1.26.3-1.el9_8 | ALSA-2026:22121 |
| AlmaLinux:8 | golang-docs | 1.25.10-1.module_el8.10.0+4187+c45165c4 | ALSA-2026:22112 |
| AlmaLinux:9 | golang-docs | 1.26.3-1.el9_8 | ALSA-2026:22121 |
| AlmaLinux:8 | golang-misc | 1.25.10-1.module_el8.10.0+4187+c45165c4 | ALSA-2026:22112 |
| AlmaLinux:9 | golang-misc | 1.26.3-1.el9_8 | ALSA-2026:22121 |
| AlmaLinux:8 | golang-race | 1.25.10-1.module_el8.10.0+4187+c45165c4 | ALSA-2026:22112 |
| AlmaLinux:9 | golang-race | 1.26.3-1.el9_8 | ALSA-2026:22121 |
| AlmaLinux:8 | golang-src | 1.25.10-1.module_el8.10.0+4187+c45165c4 | ALSA-2026:22112 |
| AlmaLinux:9 | golang-src | 1.26.3-1.el9_8 | ALSA-2026:22121 |
| AlmaLinux:8 | golang-tests | 1.25.10-1.module_el8.10.0+4187+c45165c4 | ALSA-2026:22112 |
| AlmaLinux:9 | golang-tests | 1.26.3-1.el9_8 | ALSA-2026:22121 |
| Alpine:v3.23 | go | 1.25.10-r0 | ALPINE-CVE-2026-39825 |
| Alpine:v3.24 | go | 1.26.3-r0 | ALPINE-CVE-2026-39825 |
| Alpine:v3.24 | rclone | 1.74.1-r0 | ALPINE-CVE-2026-39825 |
| Debian:12 | golang-1.19 | no fix listed | DEBIAN-CVE-2026-39825 |
| Debian:13 | golang-1.24 | no fix listed | DEBIAN-CVE-2026-39825 |
| Debian:14 | golang-1.26 | 1.26.3-1 | DEBIAN-CVE-2026-39825 |
| Go | stdlib | 1.25.10, 1.26.3 | GO-2026-4976 |
| Rocky Linux:8 | delve | 0:1.25.2-1.module+el8.10.0+40035+ee0a7047 | RLSA-2026:22112 |
| Rocky Linux:10 | golang | 0:1.26.3-4.el10_2 | RLSA-2026:22120 |
| Rocky Linux:8 | golang | 0:1.25.10-1.module+el8.10.0+40200+0fd0f175 | RLSA-2026:22112 |
| Rocky Linux:9 | golang | 0:1.26.3-1.el9_8 | RLSA-2026:22121 |
| Ubuntu:22.04:LTS | golang-1.17 | no fix listed | UBUNTU-CVE-2026-39825 |
| Ubuntu:22.04:LTS | golang-1.18 | no fix listed | UBUNTU-CVE-2026-39825 |
| Ubuntu:22.04:LTS | golang-1.20 | no fix listed | UBUNTU-CVE-2026-39825 |
| Ubuntu:22.04:LTS | golang-1.21 | no fix listed | UBUNTU-CVE-2026-39825 |
| Ubuntu:24.04:LTS | golang-1.21 | no fix listed | UBUNTU-CVE-2026-39825 |
| Ubuntu:22.04:LTS | golang-1.22 | no fix listed | UBUNTU-CVE-2026-39825 |
| Ubuntu:24.04:LTS | golang-1.22 | no fix listed | UBUNTU-CVE-2026-39825 |
| Ubuntu:22.04:LTS | golang-1.23 | no fix listed | UBUNTU-CVE-2026-39825 |
| Ubuntu:24.04:LTS | golang-1.23 | no fix listed | UBUNTU-CVE-2026-39825 |
| Ubuntu:25.10 | golang-1.23 | no fix listed | UBUNTU-CVE-2026-39825 |
| Ubuntu:26.04:LTS | golang-1.23 | no fix listed | UBUNTU-CVE-2026-39825 |
| Ubuntu:22.04:LTS | golang-1.24 | no fix listed | UBUNTU-CVE-2026-39825 |
| Ubuntu:24.04:LTS | golang-1.24 | no fix listed | UBUNTU-CVE-2026-39825 |
| Ubuntu:25.10 | golang-1.24 | no fix listed | UBUNTU-CVE-2026-39825 |
| Ubuntu:26.04:LTS | golang-1.24 | no fix listed | UBUNTU-CVE-2026-39825 |
| Ubuntu:22.04:LTS | golang-1.25 | no fix listed | UBUNTU-CVE-2026-39825 |
| Ubuntu:24.04:LTS | golang-1.25 | no fix listed | UBUNTU-CVE-2026-39825 |
| Ubuntu:25.10 | golang-1.25 | no fix listed | UBUNTU-CVE-2026-39825 |
| Ubuntu:26.04:LTS | golang-1.25 | no fix listed | UBUNTU-CVE-2026-39825 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Go standard library | net/http/httputil | 0 – before 1.25.101.26.0-0 – before 1.26.3 |