diff --git a/docs/understand/weblogs/end-to-end_weblog.md b/docs/understand/weblogs/end-to-end_weblog.md
index 08dabf6b078..60b470abf88 100644
--- a/docs/understand/weblogs/end-to-end_weblog.md
+++ b/docs/understand/weblogs/end-to-end_weblog.md
@@ -198,6 +198,20 @@ if the request to `internal_server` is a failure, it must return a json body wit
 - `status` the status code of the `internal_server` response if available or a null value
 - `error` a string describing the error, for debug purposes
 
+### GET /external_request/body_limit/{failure_reason}
+### POST /external_request/body_limit/{failure_reason}
+### TRACE /external_request/body_limit/{failure_reason}
+### PUT /external_request/body_limit/{failure_reason}
+
+Same behavior as `/external_request`, but the downstream call targets `http://internal_server:8089/downstream_response/{failure_reason}`.
+
+Supported `{failure_reason}` values (defined in `internal_server`):
+- `invalid_content_type`
+- `content_length_missing`
+- `content_length_too_big`
+
+Unknown values must return HTTP 404 with a json error body.
+
 ### GET /external_request/redirect
 
 This endpoint tests HTTP redirect chains with downstream requests, using the fastapi application in `/utils/build/docker/internal_server/app.py`
diff --git a/manifests/nodejs.yml b/manifests/nodejs.yml
index 3ea27c8774d..81a89778757 100644
--- a/manifests/nodejs.yml
+++ b/manifests/nodejs.yml
@@ -95,6 +95,7 @@ refs:
   - &ref_5_101_0 '>=5.101.0'
   - &ref_5_103_0 '>=5.103.0'
   - &ref_5_104_0 '>=5.104.0'
+  - &ref_5_106_0 '>=5.106.0'  # downstream response body limits
   - &ref_6_0_0 '>=6.0.0-pre'
 manifest:
   tests/ai_guard/test_ai_guard_sdk.py::Test_AIGuardEvent_Tag: missing_feature (APPSEC-62217)
@@ -697,6 +698,21 @@ manifest:
   tests/appsec/rasp/test_api10.py::Test_API10_request_headers: *ref_5_87_0
   tests/appsec/rasp/test_api10.py::Test_API10_request_method: *ref_5_87_0
   tests/appsec/rasp/test_api10.py::Test_API10_response_body: *ref_5_87_0
+  tests/appsec/rasp/test_api10.py::Test_API10_response_body_ignored_content_length_missing:
+    - weblog_declaration:
+        express4: *ref_5_106_0
+        express5: *ref_5_106_0
+        "*": irrelevant
+  tests/appsec/rasp/test_api10.py::Test_API10_response_body_ignored_content_length_too_big:
+    - weblog_declaration:
+        express4: *ref_5_106_0
+        express5: *ref_5_106_0
+        "*": irrelevant
+  tests/appsec/rasp/test_api10.py::Test_API10_response_body_ignored_content_type:
+    - weblog_declaration:
+        express4: *ref_5_106_0
+        express5: *ref_5_106_0
+        "*": irrelevant
   tests/appsec/rasp/test_api10.py::Test_API10_response_headers: *ref_5_87_0
   tests/appsec/rasp/test_api10.py::Test_API10_response_status: *ref_5_87_0
   tests/appsec/rasp/test_api10.py::Test_API10_without_downstream_body_analysis_using_max: *ref_5_87_0
diff --git a/tests/appsec/rasp/test_api10.py b/tests/appsec/rasp/test_api10.py
index b4e2c6aefb2..98d6fd81654 100644
--- a/tests/appsec/rasp/test_api10.py
+++ b/tests/appsec/rasp/test_api10.py
@@ -339,6 +339,78 @@ def test_api10_res_body(self):
         interfaces.library.validate_one_span(self.r, validator=self.validate_absence)
 
 
+class API10ResponseBodyIgnored(API10):
+    """Base for downstream response body guard tests."""
+
+    TAGS_NOT_EXPECTED = ["_dd.appsec.trace.res_body"]
+
+    def validate_ignored(self, span: DataDogLibrarySpan):
+        if span.get("parent_id") not in (0, None):
+            return None
+
+        if not self.validate_metric(span):
+            return None
+
+        for tag in self.TAGS_NOT_EXPECTED:
+            assert tag not in span.get("meta", {}), f"Tag {tag} should NOT be present in span's meta"
+
+        return True
+
+
+@rfc("https://docs.google.com/document/d/1gCXU3LvTH9en3Bww0AC2coSJWz1m7HcavZjvMLuDCWg/edit#heading=h.giijrtyn1fdx")
+@features.api10
+@scenarios.appsec_rasp
+class Test_API10_response_body_ignored_content_type(API10ResponseBodyIgnored):
+    """Downstream response body ignored when content-type is unsupported."""
+
+    TAGS_EXPECTED_METRIC = [
+        ("_dd.appsec.downstream_request.response_body_ignored.content_type_invalid", "1"),
+    ]
+
+    def setup_api10_response_body_ignored_content_type(self):
+        self.r = weblog.get("/external_request/body_limit/invalid_content_type")
+
+    def test_api10_response_body_ignored_content_type(self):
+        assert self.r.status_code == 200
+        interfaces.library.validate_one_span(self.r, validator=self.validate_ignored)
+
+
+@rfc("https://docs.google.com/document/d/1gCXU3LvTH9en3Bww0AC2coSJWz1m7HcavZjvMLuDCWg/edit#heading=h.giijrtyn1fdx")
+@features.api10
+@scenarios.appsec_rasp
+class Test_API10_response_body_ignored_content_length_missing(API10ResponseBodyIgnored):
+    """Downstream response body ignored when content-length is missing."""
+
+    TAGS_EXPECTED_METRIC = [
+        ("_dd.appsec.downstream_request.response_body_ignored.content_length_missing", "1"),
+    ]
+
+    def setup_api10_response_body_ignored_content_length_missing(self):
+        self.r = weblog.get("/external_request/body_limit/content_length_missing")
+
+    def test_api10_response_body_ignored_content_length_missing(self):
+        assert self.r.status_code == 200
+        interfaces.library.validate_one_span(self.r, validator=self.validate_ignored)
+
+
+@rfc("https://docs.google.com/document/d/1gCXU3LvTH9en3Bww0AC2coSJWz1m7HcavZjvMLuDCWg/edit#heading=h.giijrtyn1fdx")
+@features.api10
+@scenarios.appsec_rasp
+class Test_API10_response_body_ignored_content_length_too_big(API10ResponseBodyIgnored):
+    """Downstream response body ignored when content-length exceeds maxBytes."""
+
+    TAGS_EXPECTED_METRIC = [
+        ("_dd.appsec.downstream_request.response_body_ignored.content_length_too_big", "1"),
+    ]
+
+    def setup_api10_response_body_ignored_content_length_too_big(self):
+        self.r = weblog.get("/external_request/body_limit/content_length_too_big")
+
+    def test_api10_response_body_ignored_content_length_too_big(self):
+        assert self.r.status_code == 200
+        interfaces.library.validate_one_span(self.r, validator=self.validate_ignored)
+
+
 @rfc("https://docs.google.com/document/d/1gCXU3LvTH9en3Bww0AC2coSJWz1m7HcavZjvMLuDCWg/edit#heading=h.giijrtyn1fdx")
 @features.api10
 @scenarios.appsec_rasp
diff --git a/utils/_context/_scenarios/appsec_rasp.py b/utils/_context/_scenarios/appsec_rasp.py
index 4d797e034a6..200bb3413f8 100644
--- a/utils/_context/_scenarios/appsec_rasp.py
+++ b/utils/_context/_scenarios/appsec_rasp.py
@@ -24,6 +24,7 @@ def __init__(
             # added to test Test_ExtendedRequestBodyCollection
             "DD_APPSEC_RASP_COLLECT_REQUEST_BODY": "true",
             "DD_API_SECURITY_DOWNSTREAM_BODY_ANALYSIS_SAMPLE_RATE": "1.0",
+            "DD_API_SECURITY_MAX_DOWNSTREAM_BODY_BYTES": "128",
             "OPENAI_BASE_URL": "http://internal_server:8089",
         }
         merged_env = default_env | weblog_env
diff --git a/utils/build/docker/internal_server/app.py b/utils/build/docker/internal_server/app.py
index ecec8be5eac..3810ba46795 100644
--- a/utils/build/docker/internal_server/app.py
+++ b/utils/build/docker/internal_server/app.py
@@ -40,6 +40,45 @@ async def mirror(status: int, request: fastapi.Request):
     return fastapi.responses.JSONResponse({"status": "OK", "payload": body}, status_code=status, headers=query)
 
 
+_DOWNSTREAM_RESPONSE_BODY = b'{"ok":true}'
+_DOWNSTREAM_RESPONSE_BODY_TOO_BIG = b'{"payload":"' + b"x" * 180 + b'"}'
+
+
+@app.get("/downstream_response/{profile}")
+async def downstream_response(profile: str):
+    """Controlled downstream responses for API10 response body limit guards."""
+
+    if profile == "invalid_content_type":
+        return fastapi.responses.Response(
+            content=_DOWNSTREAM_RESPONSE_BODY,
+            status_code=200,
+            media_type="text/html",
+            headers={"content-length": str(len(_DOWNSTREAM_RESPONSE_BODY))},
+        )
+
+    if profile == "content_length_missing":
+
+        async def body_stream():
+            yield _DOWNSTREAM_RESPONSE_BODY
+
+        return fastapi.responses.StreamingResponse(
+            body_stream(),
+            status_code=200,
+            media_type="application/json",
+        )
+
+    if profile == "content_length_too_big":
+        body = _DOWNSTREAM_RESPONSE_BODY_TOO_BIG
+        return fastapi.responses.Response(
+            content=body,
+            status_code=200,
+            media_type="application/json",
+            headers={"content-length": str(len(body))},
+        )
+
+    return fastapi.responses.JSONResponse({"error": "unknown profile"}, status_code=404)
+
+
 @app.get("/redirect", response_class=fastapi.responses.RedirectResponse)
 async def redirect(request: fastapi.Request):
     """Redirect endpoint for testing API 10 with redirects
diff --git a/utils/build/docker/nodejs/express/app.js b/utils/build/docker/nodejs/express/app.js
index e21e24ddeae..a8e7a7589f7 100644
--- a/utils/build/docker/nodejs/express/app.js
+++ b/utils/build/docker/nodejs/express/app.js
@@ -664,12 +664,20 @@ app.get('/add_event', (req, res) => {
   res.status(200).json({ message: 'Event added' })
 })
 
-app.all('/external_request', (req, res) => {
+const DOWNSTREAM_RESPONSE_BODY_LIMIT_PROFILES = new Set([
+  'invalid_content_type',
+  'content_length_missing',
+  'content_length_too_big'
+])
+
+function forwardExternalRequest (req, res, downstreamPath) {
   const status = req.query.status || '200'
   const urlExtra = req.query.url_extra || ''
 
   const headers = {}
+  const queryParamsExcludedFromHeaders = new Set(['status', 'url_extra'])
   for (const [key, value] of Object.entries(req.query)) {
+    if (queryParamsExcludedFromHeaders.has(key)) continue
     headers[key] = String(value)
   }
 
@@ -679,10 +687,12 @@ app.all('/external_request', (req, res) => {
     headers['Content-Type'] = req.headers['content-type'] || 'application/json'
   }
 
+  const path = downstreamPath || `/mirror/${status}${urlExtra}`
+
   const options = {
     hostname: 'internal_server',
     port: 8089,
-    path: `/mirror/${status}${urlExtra}`,
+    path,
     method: req.method,
     headers
   }
@@ -703,12 +713,25 @@ app.all('/external_request', (req, res) => {
     })
   })
 
-  // Write body if present
   if (body) {
     request.write(body)
   }
 
   request.end()
+}
+
+app.all('/external_request', (req, res) => {
+  forwardExternalRequest(req, res)
+})
+
+app.all('/external_request/body_limit/:failureReason', (req, res) => {
+  const { failureReason } = req.params
+  if (!DOWNSTREAM_RESPONSE_BODY_LIMIT_PROFILES.has(failureReason)) {
+    res.status(404).json({ error: 'unknown failure reason' })
+    return
+  }
+
+  forwardExternalRequest(req, res, `/downstream_response/${failureReason}`)
 })
 
 app.get('/external_request/redirect', (req, res) => {
diff --git a/utils/telemetry/intake/static/config_norm_rules.json b/utils/telemetry/intake/static/config_norm_rules.json
index 04b47cae964..0841c64e550 100644
--- a/utils/telemetry/intake/static/config_norm_rules.json
+++ b/utils/telemetry/intake/static/config_norm_rules.json
@@ -21,6 +21,7 @@
     "DD_API_SECURITY_ENDPOINT_COLLECTION_MESSAGE_LIMIT": "api_security_endpoint_collection_message_limit",
     "DD_API_SECURITY_MAX_CONCURRENT_REQUESTS": "api_security_max_concurrent_requests",
     "DD_API_SECURITY_MAX_DOWNSTREAM_REQUEST_BODY_ANALYSIS": "api_security_max_downstream_request_body_analysis",
+    "DD_API_SECURITY_MAX_DOWNSTREAM_BODY_BYTES": "api_security_max_downstream_body_bytes",
     "DD_API_SECURITY_REQUEST_SAMPLE_RATE": "api_security_request_sample_rate",
     "DD_API_SECURITY_SAMPLE_DELAY": "api_security_sample_delay",
     "DD_APM_ENABLE_RARE_SAMPLER": "trace_rare_sampler_enabled",