Overview
CVE-2025-7921 is a critical vulnerability identified in certain modem models developed by Askey. This Stack-based Buffer Overflow vulnerability allows unauthenticated remote attackers to compromise the modem, potentially impacting both individual and enterprise users. The severity of this vulnerability lies in its potential to allow unauthorized execution of arbitrary code, which can lead to system compromise or data leakage. Given that modems are essential components of our digital infrastructure, this vulnerability necessitates prompt attention and remediation.
Vulnerability Summary
CVE ID: CVE-2025-7921
Severity: Critical (9.8 CVSS Severity Score)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: System compromise and potential data leakage
Affected Products
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Product | Affected Versions
Askey Modem | All Versions
How the Exploit Works
The exploit takes advantage of a stack-based buffer overflow vulnerability in the affected Askey modems. An attacker can send specially crafted packets to the modem, which, due to inadequate validation, can overflow the stack buffer. This overflow can corrupt the memory and allow the attacker to control the program’s execution flow, potentially leading to the execution of arbitrary code.
Conceptual Example Code
The below pseudocode illustrates the potential exploitation of the vulnerability. This is a simplified conceptual representation and does not represent a real attack.
POST /vulnerable_modem_endpoint HTTP/1.1
Host: target_modem_ip_address
Content-Type: application/octet-stream
{ "buffer_overflow_payload": "A"*5000 }In the above example, the “buffer_overflow_payload” involves sending a packet that is larger than what the buffer can handle (‘A’*5000). This can result in a buffer overflow, altering the execution flow of the program.
Recommended Mitigation
The immediate recommended action to mitigate this critical vulnerability is to apply the vendor-provided patch. Users are advised to contact Askey or their service provider to get the necessary updates. In scenarios where immediate patching is not possible, using a Web Application Firewall (WAF) or Intrusion Detection System (IDS) can provide a temporary mitigation. However, these should not be considered long-term solutions, as they might not fully prevent all potential exploits of this vulnerability. Regular patching and updates are key to maintaining a secure environment.