Security

• server: Stop reading from connections when flooded by HTTP/2 frames to mitigate resource exhaustion. The default value for this limit is 100 frames, excluding DATA and HEADERS, and may be changed by setting environment variable GRPC_GO_EXPERIMENTAL_CONTROL_BUFFER_THROTTLE_LIMIT.
• xds/rbac: Support Metadata and RequestedServerName permissions matcher fields. If present in a DENY rule, previously these would be ignored and fail-open.
• xds/rbac: Fix panic when parsing unsupported fields in NotRule/NotId permissions.
• xds/rbac: Support the deprecated source_ip principal identifier by treating it as equivalent to direct_remote_ip.
• xds: Fix panic when parsing route header matchers configured with empty exact_match, prefix_match, or suffix_match strings. (#9223)

New Features

• xds/googlec2p: Enable DirectPath over Interconnect support for on-premises clients via the force-xds target URI query parameter. (#9133)
• xds: Enable xDS configuration to control which fields get propagated from ORCA backend metric reports to LRS load reports. (#9145)
• authz: Add OnPolicyUpdate callback to FileWatcherOptions to notify when an authz policy is loaded or updated. (#9142)
  • Special Thanks: @hnefatl
• xds: Add support for the GCP Authentication HTTP Filter, which automatically fetches and attaches GCP Service Account Identity JWT tokens to outgoing RPCs.
  • This feature can be enabled by setting environment variable GRPC_EXPERIMENTAL_XDS_GCP_AUTHENTICATION_FILTER=true. (#9119)
• xds: Add support for xDS-based HTTP CONNECT proxies.
  • This feature can be enabled by setting environment variable GRPC_EXPERIMENTAL_XDS_HTTP_CONNECT=true. (#9151)
• xds: Add support for contains_match in route header matchers. (#9223)

Bug Fixes

• credentials/alts: Fix panic when processing malformed frames by validating that the message frame length exceeds the message type field size. (#9197)
• grpc: Fix compilation on Plan 9 targets (GOOS=plan9), broken since v1.81.0. (#9255)
  • Special Thanks: @Yusufihsangorgel