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How the mentioned CVE works:
The vulnerability exists within the `jhttpd` component of the D-Link DI-7100G C1 router, specifically in the `/webchat/login.cgi` file’s `sub_4C0990` function. The flaw is triggered by sending an overly long string as the `openid` argument in an HTTP request. This input is not properly sanitized or bounds-checked before being copied into a fixed-size stack-based buffer. The subsequent buffer overflow allows a remote, unauthenticated attacker to overwrite adjacent memory, including the function’s return address. By precisely crafting the payload, an attacker can achieve arbitrary code execution on the device with root privileges, as the `jhttpd` process typically runs with high system permissions.
Platform: D-Link DI-7100G C1
Version: Up to 20250928
Vulnerability: Buffer Overflow
Severity: Critical
date: 10/06/2025
Prediction: Patch expected Q1 2026
What Undercode Say:
`curl -X POST http://
`pattern_create.rb -l 1500`
`gdb-multiarch -q /usr/bin/jhttpd`
`(gdb) run -p 80`
`disas sub_4C0990`
How Exploit:
Remote code execution.
Overflow via openid parameter.
Hijack control flow.
Execute shellcode.
Protection from this CVE:
Block WAN access.
Await vendor patch.
Disable unused services.
Impact:
Complete system compromise.
Unauthenticated remote attack.
Permanent device backdoor.
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Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
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