CVE-2026-39825

Name	CVE-2026-39825
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.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
golang-1.15 (PTS)	bullseye	1.15.15-1~deb11u4	vulnerable
golang-1.19 (PTS)	bookworm	1.19.8-2	vulnerable
golang-1.24 (PTS)	trixie	1.24.4-1	vulnerable
golang-1.25 (PTS)	forky	1.25.9-1	vulnerable
	sid	1.25.10-1	fixed
golang-1.26 (PTS)	forky	1.26.2-3	vulnerable
	sid	1.26.3-1	fixed

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version
golang-1.15	source	(unstable)	(unfixed)
golang-1.19	source	(unstable)	(unfixed)
golang-1.24	source	(unstable)	(unfixed)
golang-1.25	source	(unstable)	1.25.10-1
golang-1.26	source	(unstable)	1.26.3-1

https://go-review.googlesource.com/c/go/+/770541
https://github.com/golang/go/issues/78948
https://groups.google.com/g/golang-announce/c/qcCIEXso47M