CVE-2026-0794: ALGO 8180 IP Audio Alerter RCE Vulnerability

CVE-2026-0794 Overview

CVE-2026-0794 is a use-after-free vulnerability [CWE-416] in the ALGO 8180 IP Audio Alerter device. The flaw resides in the Session Initiation Protocol (SIP) call handling logic. Remote attackers can execute arbitrary code on affected devices without authentication. The issue stems from operating on an object without first validating its existence.

The Zero Day Initiative tracked this issue as ZDI-CAN-28303 and published advisory ZDI-26-016. Successful exploitation grants code execution in the context of the device firmware, potentially compromising audio paging, mass notification, and emergency alerting infrastructure that depends on the 8180 endpoint.

Critical Impact
Unauthenticated remote attackers can execute arbitrary code on ALGO 8180 IP Audio Alerter devices by sending crafted SIP traffic, fully compromising the device.

Affected Products

ALGO 8180 IP Audio Alerter Firmware version 5.5
ALGO 8180 IP Audio Alerter (hardware)
Deployments exposing SIP services to untrusted networks

Discovery Timeline

2026-01-23 - CVE-2026-0794 published to NVD
2026-02-18 - Last updated in NVD database

Technical Details for CVE-2026-0794

Vulnerability Analysis

The vulnerability is a use-after-free condition in the SIP call handling component of the 8180 firmware. SIP is the signaling protocol used to establish, modify, and terminate voice sessions on IP networks. The 8180 firmware allocates objects to represent SIP call state during message processing. A code path operates on one of these objects without verifying that the object still exists.

When the referenced object has already been released, the firmware dereferences memory that an attacker can influence. Use-after-free conditions on embedded devices typically allow attackers to redirect execution by overwriting freed heap chunks with attacker-controlled data. The Zero Day Initiative advisory ZDI-26-016 documents the root cause as missing object existence validation prior to use.

Root Cause

The root cause is missing lifetime validation on a SIP-related object [CWE-416]. The firmware fails to confirm that the object pointer references a live allocation before invoking operations on it. Race conditions, premature release during error handling, or session teardown paths typically produce this class of bug. Embedded SIP stacks that share state between signaling threads are especially prone to such dangling references.

Attack Vector

The attack vector is network-based and requires no authentication or user interaction. An attacker sends a sequence of crafted SIP messages to the 8180 device on the SIP signaling port, typically UDP/5060 or TCP/5060. The crafted sequence triggers the vulnerable code path that operates on the freed object. By spraying the heap with controlled SIP payloads, an attacker can place exploitable data into the freed region and gain code execution in the device context.

Devices reachable from the internet, or from segments containing untrusted endpoints, face the highest exposure. Refer to the Zero Day Initiative Advisory ZDI-26-016 for additional technical context.

Detection Methods for CVE-2026-0794

Indicators of Compromise

Unexpected reboots, crashes, or watchdog resets on ALGO 8180 devices following inbound SIP traffic
SIP INVITE, REGISTER, or BYE message bursts from a single source to 8180 endpoints
Outbound connections from 8180 devices to unfamiliar external IP addresses
Anomalous audio playback or paging events not initiated by the management console

Detection Strategies

Inspect SIP traffic with a network intrusion detection system for malformed headers, abnormal Call-ID reuse, and rapid session teardown sequences targeting 8180 hosts
Baseline normal SIP message rates per endpoint and alert on deviations toward IP audio devices
Correlate firmware crash telemetry, where available, with preceding SIP traffic

Monitoring Recommendations

Forward switch and firewall logs covering the VoIP VLAN to a centralized analytics platform
Monitor for unauthenticated SIP signaling reaching audio appliances from non-PBX sources
Track configuration drift on 8180 devices, including unexpected firmware version changes

How to Mitigate CVE-2026-0794

Immediate Actions Required

Restrict SIP signaling to the 8180 device so it accepts traffic only from authorized PBX or SIP server addresses
Remove any internet exposure of UDP/5060 and TCP/5060 on 8180 endpoints
Place ALGO 8180 devices on a dedicated VoIP VLAN with strict access control lists
Inventory all 8180 hardware running firmware version 5.5 and prioritize them for patching

Patch Information

At the time of publication, the NVD entry references the Zero Day Initiative Advisory ZDI-26-016 but does not list a vendor patch URL. Administrators should contact Algo Solutions directly to confirm fixed firmware availability and apply the vendor-supplied update as soon as it is released.

Workarounds

Block inbound SIP traffic from untrusted networks at the perimeter firewall
Enforce source-IP filtering so only the corporate PBX can initiate SIP sessions with 8180 devices
Use a SIP-aware session border controller to validate and rate-limit signaling before it reaches the device
Disable SIP services on 8180 endpoints that are not actively used for paging

bash

# Example iptables rules restricting SIP to a trusted PBX (203.0.113.10)
iptables -A FORWARD -p udp --dport 5060 -d <ALGO_8180_IP> -s 203.0.113.10 -j ACCEPT
iptables -A FORWARD -p tcp --dport 5060 -d <ALGO_8180_IP> -s 203.0.113.10 -j ACCEPT
iptables -A FORWARD -p udp --dport 5060 -d <ALGO_8180_IP> -j DROP
iptables -A FORWARD -p tcp --dport 5060 -d <ALGO_8180_IP> -j DROP