Description
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 vulnerability is due to a buffer overflow when an affected device processes HTTP packets. An attacker could exploit this vulnerability by sending crafted HTTP input to the device. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition. Note: To exploit this vulnerability, the phone must be registered to Cisco Unified Communications Manager and have Web Access enabled. Web Access is disabled by default.
Affected products
cisco: desk phone 9871 firmware; cisco: desk phone 9871; cisco: desk phone 9841 firmware; cisco: desk phone 9841; cisco: desk phone 9851 firmware; cisco: desk phone 9851; cisco: desk phone 9861 firmware; cisco: desk phone 9861; cisco: ip phone 8865 firmware; cisco: ip phone 8865; cisco: ip phone 7811 firmware; cisco: ip phone 7811; cisco: ip phone 7821 firmware; cisco: ip phone 7821; cisco: ip phone 7841 firmware
References1
- sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAd… Vendor Advisory
Metrics
- CVSS 3.1
-
7.5
HIGH
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - EPSS — exploit probability
- 0% percentile: 42 · as of 9 November 2026
- CWE
- CWE-121
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