diff --git a/src/h3.c b/src/h3.c
index c412eb8ee..3e28c2e41 100644
--- a/src/h3.c
+++ b/src/h3.c
@@ -1955,6 +1955,25 @@ static ssize_t h3_rcv_buf(struct qcs *qcs, struct buffer *b, int fin)
 				h3s->st_req = H3S_ST_REQ_TRAILERS;
 			}
 			break;
+		case H3_FT_CANCEL_PUSH:
+			if (!conn_is_back(qcs->qcc->conn)) {
+				/* RFC 9114 7.2.3. CANCEL_PUSH
+				 *
+				 * If a server receives a CANCEL_PUSH frame for a push ID
+				 * that has not yet been mentioned by a PUSH_PROMISE frame, this MUST be
+				 * treated as a connection error of type H3_ID_ERROR.
+				 */
+				TRACE_ERROR("reject CANCEL_PUSH from client", H3_EV_RX_FRAME, qcs->qcc->conn, qcs);
+				qcc_set_error(qcs->qcc, H3_ERR_ID_ERROR, 1,
+				              muxc_tevt_type_proto_err);
+				qcc_report_glitch(qcs->qcc, 1);
+				goto err;
+			}
+			else {
+				/* Not supported */
+				ret = flen;
+			}
+			break;
 		case H3_FT_GOAWAY:
 			ret = h3_parse_goaway_frm(qcs->qcc->ctx, b, flen);
 			if (ret < 0) {
@@ -1963,7 +1982,6 @@ static ssize_t h3_rcv_buf(struct qcs *qcs, struct buffer *b, int fin)
 				goto err;
 			}
 			break;
-		case H3_FT_CANCEL_PUSH:
 		case H3_FT_PUSH_PROMISE:
 		case H3_FT_MAX_PUSH_ID:
 			/* Not supported */