diff --git a/.config/nextest.toml b/.config/nextest.toml
index 348c63799..6cb716248 100644
--- a/.config/nextest.toml
+++ b/.config/nextest.toml
@@ -144,10 +144,28 @@ test-group = 'e2e-reliability'
 # the guard now honours an off-by-default opt-in and this suite's source servers
 # set it (RUSTFS_REPLICATION_ALLOW_LOOPBACK_TARGET) — so the allowlist below is
 # restored.
+#
+# Security negative-auth subset (backlog#1151 sec-5): the three attacker-facing
+# S3 auth-rejection suites join the first clause above by module name —
+# presigned_negative (sec-2), negative_sigv4 (sec-1, header SigV4), and
+# admin_auth (sec-4, admin gate + root-credential lifecycle). All three use
+# RustFSTestEnvironment on a random port and are parallel-safe, so they meet the
+# smoke admission criteria unchanged. This is the wiring step that makes those
+# merged suites actually execute on every PR (they were dead until listed here).
+# A rename that drops any of them out of this filter would silently thin the
+# security gate with no CI signal, so scripts/check_security_smoke_count.sh owns
+# a count-floor guard over exactly this subset (infra-12 mechanism, floor in
+# .config/security-smoke-floor.txt), invoked from the e2e-tests job in ci.yml.
+# NOT here by topology: the GHSA-3p3x FTPS/WebDAV constant-time e2e
+# (protocols::test_protocol_core_suite) binds fixed ports and needs the
+# ftps,webdav features, so it cannot join this random-port, default-feature
+# profile; its GHSA-r5qv sibling is a unit test that already runs in the
+# test-and-lint `--all --exclude e2e_test` pass. See
+# docs/testing/security-regressions.md for the full CI-execution map.
 [profile.e2e-smoke]
 default-filter = """
     package(e2e_test) & (
-        test(/^(delete_marker_migration_semantics|version_id_regression|list_objects_v2_pagination|list_object_versions_regression|list_objects_duplicates|list_buckets_double_slash|leading_slash_key|special_chars|create_bucket_region|delete_objects_versioning|head_object_consistency|head_object_range|copy_object_metadata|copy_source_invalid_date|content_encoding|anonymous_access|bucket_policy_check|presigned_negative)_test::/)
+        test(/^(delete_marker_migration_semantics|version_id_regression|list_objects_v2_pagination|list_object_versions_regression|list_objects_duplicates|list_buckets_double_slash|leading_slash_key|special_chars|create_bucket_region|delete_objects_versioning|head_object_consistency|head_object_range|copy_object_metadata|copy_source_invalid_date|content_encoding|anonymous_access|bucket_policy_check|presigned_negative|negative_sigv4|admin_auth)_test::/)
         | test(/^replication_extension_test::(test_replication_check_succeeds_with_remote_target|test_replication_check_rejects_target_without_object_lock|test_set_remote_target_rejects_unversioned_source_bucket|test_replication_check_rejects_unversioned_source_bucket|test_replication_check_rejects_missing_replication_config|test_replication_check_rejects_invalid_bucket|test_set_remote_target_rejects_same_bucket_on_same_deployment|test_set_remote_target_rejects_unversioned_target_bucket|test_set_remote_target_update_requires_arn|test_set_remote_target_update_rejects_missing_target|test_set_remote_target_rejects_invalid_target_url|test_set_remote_target_rejects_self_signed_https_target_without_skip_tls_verify|test_set_remote_target_rejects_private_ca_https_target_without_ca_cert_pem|test_list_remote_targets_rejects_empty_bucket|test_list_remote_targets_rejects_invalid_bucket|test_remove_remote_target_rejects_missing_target|test_remove_remote_target_rejects_missing_arn|test_remove_remote_target_rejects_invalid_bucket|test_remove_remote_target_rejects_target_used_by_replication|test_delete_bucket_replication_removes_remote_target)$/)
         | test(/^reliant::lifecycle::/)
     )
diff --git a/.config/security-smoke-floor.txt b/.config/security-smoke-floor.txt
new file mode 100644
index 000000000..98a35fe08
--- /dev/null
+++ b/.config/security-smoke-floor.txt
@@ -0,0 +1,12 @@
+# Committed floor for the number of security negative-auth tests selected by the
+# e2e-smoke PR profile (see scripts/check_security_smoke_count.sh, backlog#1151
+# sec-5).
+#
+# The floor equals the exact count of e2e_test cases whose name starts with a
+# security module prefix (negative_sigv4_test, presigned_negative_test,
+# admin_auth_test) that the [profile.e2e-smoke] default-filter in
+# .config/nextest.toml selects, at the time this file was last updated. CI fails
+# if the selected count drops below this number, so a rename or removal that
+# thins the security smoke gate must update this file in the same PR.
+# Adding tests does not require a bump, but bumping keeps the guard tight.
+16
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 0e3b38fd8..b998266ab 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -435,6 +435,16 @@ jobs:
       - name: Make binary executable
         run: chmod +x ./target/debug/rustfs
 
+      # Guard the security negative-auth smoke subset (backlog#1151 sec-5)
+      # against a rename or deletion silently dropping it out of the e2e-smoke
+      # filter. The script lists what the profile selects and fails if the count
+      # of security auth-rejection tests falls below the committed floor in
+      # .config/security-smoke-floor.txt (infra-12 count-floor mechanism). Run
+      # before the smoke suite so a thinned gate fails fast; the `nextest list`
+      # here compiles the e2e_test binaries the run below reuses.
+      - name: Check security smoke subset count floor
+        run: ./scripts/check_security_smoke_count.sh check
+
       # PR smoke subset of the in-repo e2e suite (backlog#1149 ci-4). The
       # profile.e2e-smoke default-filter in .config/nextest.toml is the single
       # wiring mechanism for e2e tests in CI — extend that filter instead of
diff --git a/docs/testing/security-regressions.md b/docs/testing/security-regressions.md
index 49dd1efc8..f0b5740d5 100644
--- a/docs/testing/security-regressions.md
+++ b/docs/testing/security-regressions.md
@@ -22,21 +22,45 @@ forced to update its pinned test (red -> green).
 | [GHSA-r5qv-rc46-hv8q](https://github.com/rustfs/rustfs/security/advisories/GHSA-r5qv-rc46-hv8q) | Internode RPC authentication must fail closed | rustfs/rustfs#4402 | `ghsa_r5qv_resolve_shared_secret_rejects_default_fallback`, `ghsa_r5qv_verify_rpc_signature_fails_closed_on_missing_or_invalid_auth` (`crates/ecstore/src/cluster/rpc/http_auth.rs`) | unit |
 | [GHSA-m77q-r63m-pj89](https://github.com/rustfs/rustfs/security/advisories/GHSA-m77q-r63m-pj89) | STS JWTs signed with shared root secret (intentionally unfixed) | n/a | `test_created_sts_credentials_authorize_with_session_token_claims` (`crates/iam/src/sys.rs`) — pins current behavior; sec-7 adds GHSA naming | unit |
 
-## Where these run
+## Where these run (CI-execution map)
 
-- **Unit tests** (`ghsa_r5qv_*` in `crates/ecstore`) run automatically in the
-  default CI pass via `cargo nextest run` / `cargo test` — no special wiring.
-- **Protocol e2e tests** (WebDAV/FTPS constant-time login rejection) live in the
-  `e2e_test` protocols suite, which binds **fixed ports** and requires
-  `--test-threads=1`. Because of the fixed ports they **cannot** join the
-  `e2e-smoke` nextest profile (parallel, dynamic ports). They run manually today:
+Every security regression must land where CI actually runs it — a named test in
+an unexecuted suite is theater. The suites split across three execution paths by
+topology:
+
+- **Unit tests** — `ghsa_r5qv_*` (`crates/ecstore`) and the GHSA-m77q STS
+  pinning (`crates/iam`) run automatically in the default CI pass
+  (`cargo nextest run --profile ci --all --exclude e2e_test`) — no special
+  wiring. This is the CI-executed regression for the RPC fail-closed (r5qv) and
+  STS-signing (m77q) advisories.
+- **S3-API negative-auth e2e (e2e-smoke, PR-gated)** — the attacker-facing S3
+  auth-rejection suites run on every PR via the `e2e-smoke` nextest profile
+  (`.config/nextest.toml`), which each spawns its own server on a random port
+  and is parallel-safe:
+  - `negative_sigv4_test` — tampered/wrong-key/skewed header SigV4 (sec-1)
+  - `presigned_negative_test` — expired/tampered/wrong-key presigned URLs (sec-2)
+  - `admin_auth_test` — non-admin denial + root-credential lifecycle (sec-4)
+
+  A count-floor guard (`scripts/check_security_smoke_count.sh`, floor in
+  `.config/security-smoke-floor.txt`) runs in the `e2e-tests` CI job and fails if
+  a rename drops any of these out of the smoke filter (infra-12 mechanism). This
+  is the sec-5 wiring: those merged suites were dead weight until listed here.
+- **Protocol e2e (WebDAV/FTPS constant-time login, GHSA-3p3x)** — lives in the
+  `e2e_test` protocols suite (`test_protocol_core_suite`), which binds **fixed
+  ports**, needs the `ftps,webdav` build features, and is `#[serial]`. Those
+  three properties make it **structurally incompatible** with the random-port,
+  default-feature, parallel `e2e-smoke` profile: it cannot be a filterset change,
+  so sec-5 (scoped to a filterset change, global ruling G5) does not wire it.
+  It runs manually today:
 
   ```bash
   RUSTFS_BUILD_FEATURES=ftps,webdav cargo test --package e2e_test \
     test_protocol_core_suite -- --test-threads=1 --nocapture
   ```
 
-  Wiring the security e2e lane into CI is tracked separately (sec-5, backlog#1151).
+  **Open gap:** GHSA-3p3x's *e2e* layer has no PR-gated CI execution. A protocols
+  e2e CI lane is a ci-domain concern (a new profile/job, not a filterset change);
+  it is deliberately out of sec-5's boundary and left as a follow-up.
 
 ## Adding a new advisory guard
 
@@ -44,5 +68,8 @@ forced to update its pinned test (red -> green).
 2. Name the test (or the helper/assertion) `ghsa_<id>_*`, or attach a
    `GHSA-<id>` doc comment with the advisory URL and fix PR.
 3. Add a row to the table above.
-4. Land the unit-level guard where the default CI pass runs it; land any e2e
-   guard in the protocols suite (and register it with sec-5's filterset seam).
+4. Land it where CI runs it (see the map above): a unit guard in the default CI
+   pass; an S3-API negative-auth e2e in the `e2e-smoke` filter (add the module to
+   `.config/nextest.toml` and bump `.config/security-smoke-floor.txt`); a
+   fixed-port protocol e2e in the protocols suite (still manual — see the open
+   gap above).
diff --git a/scripts/check_security_smoke_count.sh b/scripts/check_security_smoke_count.sh
new file mode 100755
index 000000000..aa5f6269d
--- /dev/null
+++ b/scripts/check_security_smoke_count.sh
@@ -0,0 +1,85 @@
+#!/usr/bin/env bash
+# Count-floor guard for the security negative-auth smoke subset (backlog#1151
+# sec-5), built on the infra-12 mechanism (scripts/check_migration_gate_count.sh,
+# backlog#1153).
+#
+# The e2e-smoke profile in .config/nextest.toml selects tests BY MODULE NAME.
+# The three attacker-facing S3 auth-rejection suites — negative_sigv4_test
+# (header SigV4, sec-1), presigned_negative_test (presigned URL, sec-2), and
+# admin_auth_test (admin gate + root-credential lifecycle, sec-4) — are wired
+# into that filter so they run on every PR. A rename that drops a suite out of
+# the filter (or a deletion) silently thins the security gate to nothing with no
+# CI signal, exactly the failure mode the migration-gate guard was built for.
+#
+# This script lists what the e2e-smoke profile ACTUALLY selects and counts the
+# security suites among them, then fails when that number drops below the
+# committed floor in .config/security-smoke-floor.txt. Because it lists via the
+# profile (not a standalone name filter), it verifies real smoke MEMBERSHIP: a
+# suite renamed without updating the nextest.toml filter stops being selected,
+# its tests vanish from the listing, and the count falls below the floor. To
+# shrink the subset intentionally, update the floor file in the same PR so the
+# reduction is explicit and reviewable (adding tests never requires a bump —
+# the floor is a lower bound — but bumping keeps the guard tight).
+#
+# NAMING CONVENTION DEPENDENCY: the security suites are matched by these
+# reserved module-name prefixes:
+#
+#   negative_sigv4_test, presigned_negative_test, admin_auth_test
+#
+# Renaming a suite away from all of these prefixes removes it from the count.
+# Keep this regex in sync with the module names in the e2e-smoke filter.
+#
+# Usage:
+#   scripts/check_security_smoke_count.sh          # count check (alias of check)
+#   scripts/check_security_smoke_count.sh check    # count check only
+
+set -euo pipefail
+
+cd "$(dirname "$0")/.."
+
+# Anchored module-name prefixes of the security negative-auth smoke subset.
+# Kept deliberately in lockstep with the e2e-smoke filter in .config/nextest.toml.
+SECURITY_SMOKE_REGEX='^(negative_sigv4|presigned_negative|admin_auth)_test::'
+FLOOR_FILE=".config/security-smoke-floor.txt"
+
+mode="${1:-check}"
+case "$mode" in
+    all | check) ;;
+    *)
+        echo "usage: $0 [check]" >&2
+        exit 2
+        ;;
+esac
+
+floor="$(grep -Ev '^[[:space:]]*(#|$)' "$FLOOR_FILE" | head -n1 | tr -d '[:space:]')"
+if ! [[ "$floor" =~ ^[0-9]+$ ]]; then
+    echo "error: $FLOOR_FILE does not contain a numeric floor (got: '$floor')" >&2
+    exit 1
+fi
+
+# List via the e2e-smoke PROFILE so the default-filter is applied: only the
+# tests the PR smoke suite would actually run appear in the output. Count the
+# ones whose test name starts with a security module prefix. The structured JSON
+# listing is used (not the human format) for the same reason infra-12 does: the
+# human format's indentation varies across nextest versions; a JSON schema change
+# makes jq fail loudly rather than silently collapsing the count to zero.
+count="$(cargo nextest list --profile e2e-smoke -p e2e_test --message-format json \
+    | jq --arg re "$SECURITY_SMOKE_REGEX" \
+        '[."rust-suites"[].testcases | to_entries[] | select(.key | test($re))] | length')"
+if ! [[ "$count" =~ ^[0-9]+$ ]]; then
+    echo "error: could not parse nextest JSON listing (got count: '$count')" >&2
+    exit 1
+fi
+
+if ((count < floor)); then
+    echo "error: e2e-smoke selects $count security auth-rejection tests, below the committed floor of $floor." >&2
+    echo "" >&2
+    echo "The security smoke subset is matched by module name (negative_sigv4_test /" >&2
+    echo "presigned_negative_test / admin_auth_test) in the e2e-smoke default-filter" >&2
+    echo "(.config/nextest.toml). A rename or removal has dropped one out of the smoke" >&2
+    echo "suite. Either restore the module names (and this script's regex), or — if the" >&2
+    echo "reduction is intentional — update $FLOOR_FILE in this PR so the" >&2
+    echo "security-gate change is explicit and reviewable." >&2
+    exit 1
+fi
+echo "security smoke count OK: $count selected auth-rejection tests (floor: $floor)"