Add vpatch-CVE-2026-20253 rule and test

.appsec-tests/vpatch-CVE-2026-20253/CVE-2026-20253.yaml

@@ -0,0 +1,20 @@
+## autogenerated on 2026-06-15 09:58:35
+id: CVE-2026-20253
+info:
+  name: CVE-2026-20253
+  author: crowdsec
+  severity: info
+  description: CVE-2026-20253 testing
+  tags: appsec-testing
+http:
+  - raw:
+      - |
+        POST /en-US/splunkd/__raw/v1/postgres/recovery/backup HTTP/1.1
+        Host: {{Hostname}}
+        Authorization: Basic ZGFnOg==
+
+    cookie-reuse: true
+    matchers:
+    - type: status
+      status:
+       - 403

.appsec-tests/vpatch-CVE-2026-20253/config.yaml

@@ -0,0 +1,5 @@
+## autogenerated on 2026-06-15 09:58:35
+appsec-rules:
+  - ./appsec-rules/crowdsecurity/base-config.yaml
+  - ./appsec-rules/crowdsecurity/vpatch-CVE-2026-20253.yaml
+nuclei_template: CVE-2026-20253.yaml

appsec-rules/crowdsecurity/vpatch-CVE-2026-20253.yaml

@@ -0,0 +1,25 @@
+## autogenerated on 2026-06-15 09:58:35
+name: crowdsecurity/vpatch-CVE-2026-20253
+description: 'Detects unauthenticated file upload/truncation via Splunk PostgreSQL sidecar backup endpoint.'
+rules:
+  - and:
+      - zones:
+          - URI
+        transform:
+          - lowercase
+          - urldecode
+        match:
+          type: contains
+          value: /splunkd/__raw/v1/postgres/recovery/backup
+
+labels:
+  type: exploit
+  service: http
+  confidence: 3
+  spoofable: 0
+  behavior: 'http:exploit'
+  label: 'Splunk - Unrestricted File Upload'
+  classification:
+    - cve.CVE-2026-20253
+    - attack.T1190
+    - cwe.CWE-434

collections/crowdsecurity/appsec-virtual-patching.yaml

@@ -48,6 +48,7 @@ appsec-rules:
 - crowdsecurity/vpatch-CVE-2023-35078
 - crowdsecurity/vpatch-CVE-2023-35082
 - crowdsecurity/vpatch-CVE-2023-24000
+- crowdsecurity/vpatch-CVE-2026-20253
 - crowdsecurity/vpatch-CVE-2022-22954
 - crowdsecurity/vpatch-CVE-2024-1212
 - crowdsecurity/vpatch-symfony-profiler