vpatch rule for CVE-2026-41940 (#1784)

Author: buixor

.appsec-tests/vpatch-CVE-2026-41940/CVE-2026-41940.yaml

@@ -0,0 +1,32 @@
+id: CVE-2026-41940
+info:
+  name: CVE-2026-41940
+  author: crowdsec
+  severity: info
+  description: CVE-2026-41940 testing - cPanel WHM auth bypass via stripped ob cookie
+  tags: appsec-testing
+http:
+  - raw:
+      - |
+        GET / HTTP/1.1
+        Host: {{Hostname}}
+        Cookie: whostmgrsession=%3aQSJN_sFdKZtCi2o_
+        Authorization: Basic cm9vdDp4DQpoYXNyb290PTENCnRmYV92ZXJpZmllZD0xDQp1c2VyPXJvb3Q=
+      - |
+        GET / HTTP/1.1
+        Host: {{Hostname}}
+        Cookie: whostmgrsession=%3aQSJN_sFdKZtCi2o_%2C
+        Authorization: Basic cm9vdDp4DQpoYXNyb290PTENCnRmYV92ZXJpZmllZD0xDQp1c2VyPXJvb3Q=
+      - |
+        GET / HTTP/1.1
+        Host: {{Hostname}}
+        Cookie: whostmgrsession=%3aQSJN_sFdKZtCi2o_%2Ctoto
+        Authorization: Basic cm9vdDp4DQpoYXNyb290PTENCnRmYV92ZXJpZmllZD0xDQp1c2VyPXJvb3Q=
+    cookie-reuse: true
+    matchers:
+    - type: dsl
+      condition: and
+      dsl:
+        - 'status_code_1 == 403'
+        - 'status_code_2 == 403'
+        - 'status_code_3 == 200'

.appsec-tests/vpatch-CVE-2026-41940/config.yaml

@@ -0,0 +1,4 @@
+appsec-rules:
+  - ./appsec-rules/crowdsecurity/base-config.yaml
+  - ./appsec-rules/crowdsecurity/vpatch-CVE-2026-41940.yaml
+nuclei_template: CVE-2026-41940.yaml

appsec-rules/crowdsecurity/vpatch-CVE-2026-41940.yaml

@@ -0,0 +1,27 @@
+name: crowdsecurity/vpatch-CVE-2026-41940
+description: 'Detects cPanel & WHM authentication bypass (CVE-2026-41940) by identifying a whostmgrsession cookie with a stripped ob segment (no comma separator)'
+rules:
+  - and:
+      - zones:
+          - COOKIES
+        variables:
+          - whostmgrsession
+        transform:
+          - lowercase
+          - urldecode
+          - trim
+        match:
+          type: regex
+          value: '^:[a-z0-9_]+,?$'
+
+labels:
+  type: exploit
+  service: http
+  confidence: 3
+  spoofable: 0
+  behavior: 'http:exploit'
+  label: 'cPanel WHM - Authentication Bypass'
+  classification:
+    - cve.CVE-2026-41940
+    - attack.T1190
+    - cwe.CWE-306

collections/crowdsecurity/appsec-virtual-patching.yaml

@@ -185,6 +185,7 @@ appsec-rules:
 - crowdsecurity/vpatch-CVE-2025-24582
 - crowdsecurity/vpatch-CVE-2025-15503
 - crowdsecurity/vpatch-CVE-2025-13956
+- crowdsecurity/vpatch-CVE-2026-41940
 author: crowdsecurity
 contexts:
 - crowdsecurity/appsec_base