The "Cloudflare Memory Leak," dubbed "Cloudbleed," occurred in February 2017.

It The "Cloudflare Memory Leak," dubbed "Cloudbleed," occurred in February 2017.

It was a critical software vulnerability affecting Cloudflare's reverse proxy infrastructure. The root cause was a bug in a specific HTML parser (`cf-html`) used by Cloudflare.

This parser, when processing certain malformed HTML, would overrun its buffer due to a faulty regular expression. Instead of just the intended data, it would read and expose random chunks of memory from Cloudflare's edge servers.

This exposed memory could contain highly sensitive information, including passwords, cookies, API keys, private messages, and encryption keys, belonging to *other* Cloudflare customers. This data was then inadvertently served to subsequent visitors requesting pages.

The leak was intermittent but potentially widespread. Cloudflare identified and patched the bug swiftly, invalidated potentially compromised sessions, and worked with search engines to purge cached leaked data. It highlighted the risks of shared infrastructure and parsing errors.

=============================================================================================================================================
| # Title : Cloudflare Memory Leak Incident |
| # Author : indoushka |
| # Tested on : windows 11 Fr(Pro) / browser : Mozilla firefox 145.0.2 (64 bits) |
| # Vendor : https://www.cloudflare.com/ |
=============================================================================================================================================

[+] References : https://packetstorm.news/files/id/212490/ &

[+] Summary : A Python-based scanner imitates CloudBleed-style leakage detection by fetching raw HTTP response data from a target website, converting it to hexadecimal,
and searching for sensitive memory patterns such as sessions, passwords, tokens, cookies, AWS keys, and stack traces.
It does not exploit the server, but identifies potential leaks revealed in the response body.


[+] POC : python poc.py

#!/usr/bin/env python3
import re
import requests
import binascii

# ================================
# CONFIG
# ================================
TARGET_URL = "https://127.0.0.1/"
TIMEOUT = 10
MAX_HEX_DUMP = None # None = unlimited

# ================================
# SIGNATURES (Memory-leak patterns)
# ================================
PATTERNS = [
(b"session", "POTENTIAL_SESSION_LEAK"),
(b"cookie", "POTENTIAL_COOKIE_LEAK"),
(b"password", "POTENTIAL_PASSWORD_LEAK"),
(b"token", "POTENTIAL_TOKEN_LEAK"),
(b"bearer", "POTENTIAL_OAUTH_LEAK"),
(b"key=", "POTENTIAL_KEY_LEAK"),
(b"aws", "POTENTIAL_AWS_LEAK"),
(b"stacktrace", "POTENTIAL_STACKTRACE_LEAK"),
(b"malloc", "POTENTIAL_ALLOCATOR_LEAK"),
(b"free(", "POTENTIAL_FREE_MEMORY_REFERENCE"),
]

# ================================
# HTTP Fetch
# ================================
def fetch():
try:
r = requests.get(TARGET_URL, timeout=TIMEOUT)
return r.content
except:
return b""

# ================================
# Hex Dump Generator (CloudBleed Style)
# ================================
def hex_dump(data):
hexd = binascii.hexlify(data).decode()
return hexd if MAX_HEX_DUMP is None else hexd[:MAX_HEX_DUMP]

# ================================
# Scanner Core
# ================================
def scan_memory():
raw = fetch()
if not raw:
print("[!] Failed to fetch target")
return

print(f"[+] Memory Size Captured: {len(raw)} bytes")
print("=" * 80)

HEX = hex_dump(raw)
print("[*] Full HEX DUMP (No Truncation):\n")
print(HEX)
print("\n" + "=" * 80)

for signature, label in PATTERNS:
if signature.lower() in raw.lower():
print(f"[!] MATCH: {label}")
print(f" Pattern: {signature}")
print(" Extract:")
idx = raw.lower().find(signature.lower())
start = max(0, idx - 64)
end = min(len(raw), idx + 512)
leak_block = raw[start:end]
print(hex_dump(leak_block))
print("-" * 60)

if __name__ == "__main__":
scan_memory()


Greetings to :=====================================================================================
jericho * Larry W. Cashdollar * LiquidWorm * Hussin-X * D4NB4R * Malvuln (John Page aka hyp3rlinx)|
===================================================================================================