Patch-Source: https://github.com/nginx/nginx/commit/131be8514da8985b15b74150521afedbf9cc4ea3

ngx_http_proxy_v2_module.c doesn't exist in 1.28, so it's removed from
the patch.
--
From 67c99f001ee697b4266f79376dd3155e4fb003a3 Mon Sep 17 00:00:00 2001
From: Roman Arutyunyan <arut@nginx.com>
Date: Tue, 2 Jun 2026 19:37:17 +0400
Subject: [PATCH] Upstream: limit header length for gRPC

The change applies the HTTP/2 header length limits to avoid buffer
overflow.  See 58a7bc3406ac for details.

Reported by Mufeed VH of Winfunc Research.
---
 src/http/modules/ngx_http_grpc_module.c | 44 +++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/src/http/modules/ngx_http_grpc_module.c b/src/http/modules/ngx_http_grpc_module.c
index e7726f314..98ba8a98f 100644
--- a/src/http/modules/ngx_http_grpc_module.c
+++ b/src/http/modules/ngx_http_grpc_module.c
@@ -740,6 +740,12 @@ ngx_http_grpc_create_request(ngx_http_request_t *r)
         tmp_len = 0;
 
     } else {
+        if (r->method_name.len > NGX_HTTP_V2_MAX_FIELD) {
+            ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                          "too long http2 method: \"%V\"", &r->method_name);
+            return NGX_ERROR;
+        }
+
         len += 1 + NGX_HTTP_V2_INT_OCTETS + r->method_name.len;
         tmp_len = r->method_name.len;
     }
@@ -760,6 +766,12 @@ ngx_http_grpc_create_request(ngx_http_request_t *r)
         uri_len = r->uri.len + escape + sizeof("?") - 1 + r->args.len;
     }
 
+    if (uri_len > NGX_HTTP_V2_MAX_FIELD) {
+        ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                      "too long http2 URI");
+        return NGX_ERROR;
+    }
+
     len += 1 + NGX_HTTP_V2_INT_OCTETS + uri_len;
 
     if (tmp_len < uri_len) {
@@ -769,6 +781,12 @@ ngx_http_grpc_create_request(ngx_http_request_t *r)
     /* :authority header */
 
     if (!glcf->host_set) {
+        if (ctx->host.len > NGX_HTTP_V2_MAX_FIELD) {
+            ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                          "too long http2 host: \"%V\"", &ctx->host);
+            return NGX_ERROR;
+        }
+
         len += 1 + NGX_HTTP_V2_INT_OCTETS + ctx->host.len;
 
         if (tmp_len < ctx->host.len) {
@@ -799,6 +817,18 @@ ngx_http_grpc_create_request(ngx_http_request_t *r)
             continue;
         }
 
+        if (key_len > NGX_HTTP_V2_MAX_FIELD) {
+            ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                          "too long http2 header name");
+            return NGX_ERROR;
+        }
+
+        if (val_len > NGX_HTTP_V2_MAX_FIELD) {
+            ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                          "too long http2 header value");
+            return NGX_ERROR;
+        }
+
         len += 1 + NGX_HTTP_V2_INT_OCTETS + key_len
                  + NGX_HTTP_V2_INT_OCTETS + val_len;
 
@@ -833,6 +863,20 @@ ngx_http_grpc_create_request(ngx_http_request_t *r)
                 continue;
             }
 
+            if (header[i].key.len > NGX_HTTP_V2_MAX_FIELD) {
+                ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                              "too long http2 header name: \"%V\"",
+                              &header[i].key);
+                return NGX_ERROR;
+            }
+
+            if (header[i].value.len > NGX_HTTP_V2_MAX_FIELD) {
+                ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                              "too long http2 header value: \"%V: %V\"",
+                              &header[i].key, &header[i].value);
+                return NGX_ERROR;
+            }
+
             len += 1 + NGX_HTTP_V2_INT_OCTETS + header[i].key.len
                      + NGX_HTTP_V2_INT_OCTETS + header[i].value.len;
 
-- 
2.55.0