# they can't keep getting away with this...

Source: https://www.youtube.com/watch?v=I4brAvpjbrg
Recap page: https://rapidrecap.app/video/I4brAvpjbrg
Generated: 2026-02-20T15:05:46.559+00:00

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## Quick Overview

The critical, unauthenticated stack buffer overflow vulnerability (CVE-2026-2329) in Grandstream GXP1600 series VoIP phones allows an attacker to gain root privileges and execute arbitrary code via the web-based API endpoint /cgi-bin/api.values.get, which lacks proper length checks on the request parameter, leading to a successful Metasploit exploitation demonstrated in the video.

**Key Points:**
- Rapid7 Labs discovered CVE-2026-2329, a critical stack buffer overflow in Grandstream GXP1600 series VoIP phones, rated CVSSv4 score of 9.3 (Critical).
- The vulnerability exists in the web-based API endpoint /cgi-bin/api.values.get, which fails to check the length of the attacker-controlled 'request' parameter, allowing data to overflow the 64-byte stack buffer.
- Exploitation grants an attacker unauthenticated Remote Code Execution (RCE) with root privileges, enabling them to steal credentials (including SIP accounts) and transparently intercept phone calls.
- The affected models share a common firmware image, impacting GXP1610, GXP1615, GXP1620, GXP1625, GXP1628, and GXP1630.
- The binary is not Position Independent Executable (PIE) and lacks stack canaries, simplifying the construction of a Return-Oriented Programming (ROP) chain for code execution.
- The recommended remediation is to upgrade to firmware version 1.0.7.81 or above.
- The video demonstrates a successful Metasploit exploitation achieving a reverse shell with root privileges (0:08:09).

![Screenshot at 0:09: The screen displays the Rapid7 blog post detailing CVE-2026-2329: Critical Unauthenticated Stack Buffer Overflow in Grandstream GXP1600 VoIP Phones \(FIXED\), setting the context for the technical deep dive.](https://ss.rapidrecap.app/screens/I4brAvpjbrg/00-00-09.jpg)

**Context:** The video details a security analysis conducted by Rapid7 Labs concerning a critical vulnerability, CVE-2026-2329, discovered in the Grandstream GXP1600 series of Voice over Internet Protocol (VoIP) phones. The vulnerability stems from a stack-based buffer overflow in the device's web administration interface API. The presenter walks through the technical analysis, demonstrating how an attacker can leverage this flaw, which lacks proper input validation, to execute arbitrary code on the affected devices.

## Detailed Analysis

The video analyzes CVE-2026-2329, a critical unauthenticated stack-based buffer overflow affecting six models of Grandstream GXP1600 VoIP phones, rated 9.3 Critical by CVSSv4. The vulnerability resides in the device's web-based API service, accessible via TCP port 80, specifically the /cgi-bin/api.values.get endpoint. This endpoint processes the colon-delimited 'request' parameter without adequate length validation, leading to a buffer overflow in a small 64-byte stack buffer called 'small_buffer'. Because there is no length check when appending characters beyond the initial 64 bytes, an attacker can overwrite adjacent stack memory, including the return address. The analysis shows the binary lacks several modern mitigations: No PIE, no stack canaries, and no No Execute (NX) protection on the stack segment, though NX is enabled. The absence of PIE allows the attacker to know the base address of the code segment, facilitating ROP chain construction. The exploit demonstrated in the video uses a Metasploit module to achieve unauthenticated RCE with root privileges, confirmed by obtaining a shell and running commands like 'getuid' which returns 'root' (0:51). Post-exploitation, the attacker can extract secrets like local and SIP account credentials and reconfigure the device to act as a malicious SIP proxy to transparently intercept phone calls. The recommended remediation is upgrading to firmware version 1.0.7.81 or later.

### Vulnerability Overview

- CVE-2026-2329 is a Critical Unauthenticated Stack Buffer Overflow in Grandstream GXP1600 series VoIP phones
- CVSSv4 score of 9.3
- Affects GXP1610, GXP1615, GXP1620, GXP1625, GXP1628, and GXP1630 models.

### Exploitation Mechanics

- The vulnerability occurs in the /cgi-bin/api.values.get endpoint which uses a vulnerable parsing function (sub_14484) that copies user-controlled data from the 'request' parameter into a small 64-byte stack buffer without sufficient length checks, allowing overflow into adjacent stack memory.

### Mitigation Deficiencies

- Checksec analysis reveals the binary lacks PIE, stack canaries, and RPATH, although NX is enabled, necessitating a Return-Oriented Programming (ROP) chain for exploitation.

### Metasploit Demonstration

- The video shows successful exploitation using a Metasploit module, resulting in a Meterpreter session with root privileges (uid=0, gid=0) on the target ARM device (0:51:19).

### Impact

- Successful exploitation allows for RCE with root privileges, extraction of credentials (local and SIP accounts), and reconfiguring the device to transparently intercept phone calls via a malicious SIP proxy.

### Remediation

- Grandstream users must upgrade their firmware to version 1.0.7.81 or above to fully remediate the vulnerability.

![Screenshot at 0:09: The screen displays the Rapid7 blog post detailing CVE-2026-2329: Critical Unauthenticated Stack Buffer Overflow in Grandstream GXP1600 VoIP Phones \(FIXED\), setting the context for the technical deep dive.](https://ss.rapidrecap.app/screens/I4brAvpjbrg/00-00-09.jpg)
![Screenshot at 0:51: The terminal output confirms successful exploitation via Metasploit, showing the Meterpreter session running with 'Server username: root' and 'uid=0\(root\) gid=0\(root\)'.](https://ss.rapidrecap.app/screens/I4brAvpjbrg/00-00-51.jpg)
![Screenshot at 2:30: A sequence of images from the movie 'Hackers' is shown while the presenter discusses using the vulnerability to reconfigure the phone to act as a malicious SIP proxy to intercept calls.](https://ss.rapidrecap.app/screens/I4brAvpjbrg/00-02-30.jpg)
![Screenshot at 5:03: The presentation shifts to decompiled C code for the vulnerable function sub\_14484, highlighting how the request parameter is parsed and how the small 64-byte stack buffer is used.](https://ss.rapidrecap.app/screens/I4brAvpjbrg/00-05-03.jpg)
![Screenshot at 7:42: The output from the checksec tool shows that the binary lacks PIE and stack canaries, which aids in exploitation, despite having NX enabled.](https://ss.rapidrecap.app/screens/I4brAvpjbrg/00-07-42.jpg)