What happened
A vulnerability identified as CVE-2026-77558 has been disclosed in certain UniFi gateway devices. This flaw is an Out-of-bounds Read vulnerability, which can be exploited remotely over a network. A malicious actor with network access could initiate a denial of service (DoS) attack against affected devices, potentially leading to device unavailability. The attack does not involve malicious code execution or data breach, but the impact on device availability is significant enough to be rated as high severity. The specific component affected is the Ubiquiti UniFi Gateway, with the vulnerability attributed to a weakness classified as CWE-125.
The exploit relies on the attacker directly targeting exposed services on the device. No prior access to the network is necessary, nor does the attacker need to perform any user interaction. The vulnerability’s exploit path involves an attacker sending crafted network traffic to the vulnerable service, which leads to an out-of-bounds read condition causing the device to crash or become unresponsive. This can result in disruption of network operations until the device recovers or is mitigated.
The severity score assigned to this vulnerability is 7.5 on the CVSS scale, with a vector indicating that the attack can be conducted over the network with no privileges or user interaction needed. At the time of writing, no patch or remediation link has been provided; mitigation efforts should focus on reducing network exposure, implementing proper segmentation, and controlling access to the affected services to prevent exploitation.
Who is affected
Organisations deploying Ubiquiti UniFi Gateway devices are potentially affected by this vulnerability. Any deployment with network-exposed UniFi gateways could be targeted if the affected components are reachable from the internet or untrusted networks. Because the vulnerability can be exploited without any user interaction or prior access, all such installations should consider their network exposure levels and control access accordingly. Details about specific device models or firmware versions are not yet available, but awareness of the vulnerability should prompt relevant security reviews for affected network gateways.
Recommended actions
- Review network configurations to ensure that access to the affected services on UniFi Gateway devices is restricted to trusted internal networks or management sources.
- Implement network segmentation practices to isolate critical infrastructure, reducing the likelihood of external threat actors reaching vulnerable services.
- Monitor network traffic for anomalies targeting UniFi Gateway devices, particularly unusual or crafted requests that could indicate scanning or exploitation attempts.
- Apply available security patches or updates once they are released and verified by the vendor that address this specific vulnerability.
- Regularly review external exposure of network gateways and minimize any unnecessary internet-facing services.
Indicators of compromise
At this time, no specific indicators of compromise or known malicious activity associated with this vulnerability have been publicly disclosed.
