CVE-2026-84445

A flaw was found in gRPC-Go. Servers created with xds.NewGRPCServer() can be exploited by a remote client sending a malformed RPC request that lacks the required :authority or Host headers. This can trigger an index-out-of-bounds panic, leading to the termination of the entire server process and a Denial of Service (DoS). In some deployments, this attack can be unauthenticated.

This vulnerability is rated as an Important severity impact because an unauthenticated remote client can crash the host daemon, causing an immediate denial of service across exposed endpoints. The issue specifically threatens deployments utilizing xDS-managed gRPC servers, as requests that omit standard routing authority parameters cause the application to crash on an unhandled slice lookup. Standard gRPC server implementations that do not configure xDS control plane routing are not susceptible to this failure mode. Furthermore, in environments enforcing mutual transport layer security (mTLS), successful transport authentication is required before reaching the vulnerable routing stage, restricting potential exploitation to authenticated peers.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.