CVE-2026-84303

Name	CVE-2026-84303
Description	gRPC-Go is the Go language implementation of gRPC. Prior to 1.83.1, the xDS RBAC HTTP filter in internal/xds/httpfilter/rbac/rbac.go does not lowercase header matcher names in normalizeHeaderMatcher even though incoming metadata keys are lowercase. A DENY policy using a mixed-case name such as X-Role or User-Agent therefore does not match and fails open, allowing requests that should be rejected. The same case mismatch permits :Scheme or Grpc-Status to evade gRFC A41 validation and prevents Host from being rewritten to :authority. This issue is fixed in version 1.83.1.
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)
Debian Bugs	1146639

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
golang-google-grpc (PTS)	bookworm	1.33.3-2	vulnerable
	trixie	1.64.0-7	vulnerable
	forky, sid	1.81.1-1	vulnerable

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
golang-google-grpc	source	(unstable)	(unfixed)			1146639

Notes

[trixie] - golang-google-grpc <no-dsa> (Minor issue)
[bookworm] - golang-google-grpc <postponed> (Limited support)
https://github.com/grpc/grpc-go/security/advisories/GHSA-qc2q-p7wx-3px3
https://github.com/grpc/grpc-go/pull/9332
Fixed by: https://github.com/grpc/grpc-go/commit/db9482836c298f234c896cf82ab68cafc78237f8 (master)
https://github.com/grpc/grpc-go/pull/9335 (v1.83.x backport)
Fixed by: https://github.com/grpc/grpc-go/commit/ebba6f3f1b206e2b4dc4d1d5a96d18430302c2fe (v1.83.1)