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.
How to fix CVE-2026-39825
To remediate CVE-2026-39825, upgrade the affected package to a fixed version below.
- —upgrade to 1.25.10 or later
- —no fix listed
- —no fix listed
- —no fix listed
- —upgrade to 1.25.10-1 or later
- —upgrade to 1.26.3-1 or later
- —upgrade to 1.25.10 or later
Is CVE-2026-39825 being exploited?
Low — EPSS is 0.0%, meaning exploitation activity has not been observed at scale.
Affected packages (7)
- from 0, < 1.25.10, >= 1.26.0-0, < 1.26.3
- from 0
- from 0
- from 0
- from 0, < 1.25.10-1
- from 0, < 1.26.3-1
- from 0, < 1.25.10, >= 1.26.0-0, < 1.26.3
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | MEDIUM5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N |