CVE-2026-20281
HighCVSS 7.5Exploitation Probability (EPSS)
Low risk26th percentile - higher than 26% of all known CVEs
Summary
A vulnerability in Cisco Desk Phone 9800 Series, IP Phone 7800 and 8800 Series, and Video Phone 8875 running SIP Software allows an unauthenticated, remote attacker to cause a DoS condition. It is due to improper memory management when processing HTTP packets, and exploitation involves sending a continuous stream of crafted HTTP packets.
Risk Assessment
The attack can cause continuous memory consumption, leading to device unavailability. A manual reboot is required, which can disrupt communications.
Recommendation
Apply Cisco-provided SIP software updates and consider disabling Web Access if not needed to reduce risk.
Other vulnerabilities in Cisco SIP Software
See all- CVE-2025-20351Medium
A vulnerability in the web UI of Cisco Desk Phone 9800 Series, IP Phone 7800/8800 Series, and Video Phone 8875 running Cisco SIP Software allows an unauthenticated, remote attacker to conduct XSS attacks against a user of the web UI. The issue exists due to insufficient validation of user-supplied input. Exploitation requires the user to click a crafted link, and the phone must be registered to Cisco Unified Communications Manager with Web Access enabled (disabled by default).
- CVE-2025-20350High
A vulnerability in the web UI of Cisco Desk Phone 9800 Series, Cisco IP Phone 7800 and 8800 Series, and Cisco Video Phone 8875 running Cisco SIP Software could allow an unauthenticated, remote attacker to cause a DoS condition on an affected device. This is due to a buffer overflow when processing HTTP packets. An attacker could exploit this by sending crafted HTTP input, causing the device to reload. To exploit, the phone must be registered to Cisco Unified Communications Manager and have Web Access enabled (disabled by default).
Original NVD description (English source)
A vulnerability in Cisco Desk Phone 9800 Series, Cisco IP Phone 7800 and 8800 Series, and Cisco Video Phone 8875 that are running Cisco Session Initiation Protocol (SIP) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to improper memory management when an affected device processes HTTP packets. An attacker could exploit this vulnerability by sending a continuous stream of crafted HTTP packets to the device. A successful exploit could allow the attacker to cause the affected device to continuously consume memory, resulting in a DoS condition. A manual reboot of the device is required to recover from this condition. Note: For this vulnerability to be exploitable, the phone must be registered to Cisco Unified Communications Manager (Unified CM) and have Web Access enabled. Web Access is disabled by default.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS