CRITICAL CVSS 9.8
Published: 2021-03-11

CVE-2021-28141

progress telerik_ui_for_asp.net_ajax Security Advisory (CVE-2021-28141)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2021-28141 impacting progress telerik_ui_for_asp.net_ajax. Evaluated with CVSS Base Score of 9.8 (CRITICAL).

Original NVD Description

Source: NIST NVD
An issue was discovered in Progress Telerik UI for ASP.NET AJAX 2021.1.224. It allows unauthorized access to MicrosoftAjax.js through the Telerik.Web.UI.WebResource.axd file. This may allow the attacker to gain unauthorized access to the server and execute code. To exploit, one must use the parameter _TSM_HiddenField_ and inject a command at the end of the URI. NOTE: the vendor states that this is not a vulnerability. The request's output does not indicate that a "true" command was executed on the server, and the request's output does not leak any private source code or data from the server

📊 CVSS v3.1 Metric Breakdown

Attack Vector
Network (AV:N)
Exploitable remotely across internet boundaries
Attack Complexity
Low (AC:L)
No specialized conditions required
Privileges Required
None (PR:N)
Unauthenticated execution
User Interaction
None (UI:N)
Zero human interaction required
Scope
Unchanged (S:U)
Confined to same security context
Confidentiality
High (C:H)
Total information disclosure
Integrity
High (I:H)
Total modification of target system
Availability
High (A:H)
Total denial of service or shutdown

🎯 Affected Versions Matrix

Affected Product progress / telerik_ui_for_asp.net_ajax
Affected Versions 2021.1.224
Weakness Enumeration CWE-862

Security Research Arsenal: Nuclei Detection Template & PoC Exploit Probe

High-Intent Research Tool

Ready-to-use security scanner signatures, active verification probe skeletons, and remediation playbooks for CVE-2021-28141 impacting progress telerik_ui_for_asp.net_ajax.

⚡ Nuclei Detection Template (YAML) cve-2021-28141.yaml
id: cve-2021-28141

info:
  name: progress telerik_ui_for_asp.net_ajax - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: critical
  description: |
    Automated signature & scanner for CVE-2021-28141 affecting progress telerik_ui_for_asp.net_ajax.
    Evaluation: An issue was discovered in Progress Telerik UI for ASP.NET AJAX 2021.1.224. It allows unauthorized access to MicrosoftAjax.js through the Telerik.Web....
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2021-28141
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
    cvss-score: 9.8
    cve-id: CVE-2021-28141
    cwe-id: CWE-862
  tags: cve,cve-2021-28141,progress,telerik_ui_for_asp.net_aj,critical

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "telerik_ui_for_asp.net_ajax"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2021-28141.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2021-28141
# Target: progress telerik_ui_for_asp.net_ajax | CVSS: 9.8 (CRITICAL)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2021-28141 (progress telerik_ui_for_asp.net_ajax)...")
    headers = {
        "User-Agent": "CyberVault-Audit-Scanner/2.0",
        "Accept": "*/*"
    }
    try:
        r = requests.get(f"{target_url.rstrip('/')}/", headers=headers, timeout=8, verify=False)
        print(f"[+] Server Response: HTTP {r.status_code} | Server Banner: {r.headers.get('Server', 'Unknown')}")
        if r.status_code < 500:
            print(f"[!] Target reachable. Verify version against progress telerik_ui_for_asp.net_ajax scope (2021.1.224).")
        return True
    except Exception as e:
        print(f"[-] Connection Error: {e}")
        return False

if __name__ == '__main__':
    url = sys.argv[1] if len(sys.argv) > 1 else "http://localhost:8080"
    verify_vulnerability(url)
🛡️ Quick Patch & Remediation Script (Bash) patch_cve-2021-28141.sh
# Recommended Remediation & Patching Commands for CVE-2021-28141
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install telerik_ui_for_asp.net_aj 2>/dev/null || \
sudo dnf upgrade telerik_ui_for_asp.net_aj 2>/dev/null || \
sudo yum update telerik_ui_for_asp.net_aj

# 2. Inspect installed package versions for vulnerable scope:
dpkg -l | grep -i telerik_ui_for_asp.net_aj 2>/dev/null || rpm -qa | grep -i telerik_ui_for_asp.net_aj

# 3. Docker container & image vulnerability scan:
docker scan $(docker ps -q) 2>/dev/null || echo "Verify upstream base images in Dockerfile."

🛡️ Remediation & Security Action

  • Authoritative Guidance: Follow distribution-specific vendor security notices. Advisory status and package patches vary by distribution release.
  • Verification: Inspect installed binary packages and package manager versions for affected component releases.
  • Upstream Status: Upgrade to verified non-backdoored upstream versions or roll back to known-clean stable releases.
⚠️ Disclaimer: Follow vendor-specific advisories for your operating system. CyberVault does not fabricate unsupported remediation scripts.

🔗 Verified Technical References

❓ Frequently Asked Questions (FAQ) & Remediation Guide

How do I fix CVE-2021-28141 in progress telerik_ui_for_asp.net_ajax?

Review vendor-specific security notices and update progress telerik_ui_for_asp.net_ajax packages to the latest patched release immediately. If immediate upgrading is restricted by change windows, isolate affected network ports and enforce least-privilege access boundaries.

Is there an active exploit or public PoC for CVE-2021-28141?

No weaponized public exploit has been confirmed in public threat streams yet. Continuous surveillance is active across GitHub and security feeds.

What is the CVSS 3.1 severity rating and impact for CVE-2021-28141?

CVE-2021-28141 is classified with a CVSS 3.1 Base Score of 9.8 (CRITICAL). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
9.8
CRITICAL SEVERITY
CVE ID CVE-2021-28141
Weakness CWE-862
Vendor progress
Product telerik_ui_for_asp.net_ajax
Published 2021-03-11
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H