On September 2, 2026, the Cisco Product Security Incident Response Team (PSIRT) published the following advisories:Cisco Security AdvisoryCVE IDSecurity Impact RatingCVSS Base ScoreCisco IOS XR Software Security Hardening Release: September 2026CVE-2026-20277CVE-2026-20278CVE-2026-20280CVE-2026-20279CVE-2026-20276CVE-2026-20275CVE-2026-20274Critical9.8Cisco Nexus 9000 Series Switches Silicon One Remote Code Execution VulnerabilityCVE-2026-20212Critical 9.8Cisco Desk Phone 9800 Series, IP Phone 7800 and 8800 Series, and Video Phone 8875 with SIP Software Denial of Service VulnerabilityCVE-2026-20281High7.5Cisco Secure Email Secure/Multipurpose Internet Mail Extensions Ciphertext Decryption VulnerabilitiesCVE-2026-20355CVE-2026-20354Medium5.9To remediate the vulnerabilities that were disclosed on September 2, 2026, Cisco strongly recommends that customers upgrade to the fixed software that is indicated in the advisories.For more information about changes in Cisco PSIRT vulnerability disclosure, see Strengthening the Foundation: A Predictable, Customer-Focused Response to AI-Accelerated Vulnerability Discovery.

A vulnerability in the web UI of Cisco Desk Phone 9800 Series, Cisco IP Phone 7800 and 8800 Series, and Cisco Video Phone 8875 could allow an unauthenticated, remote attacker to access sensitive information on an affected device. This vulnerability is due to improper storage of sensitive information within the web UI of Session Initiation Protocol (SIP)-based phone loads. An attacker could exploit this vulnerability by browsing to the IP address of a device that has Web Access enabled. A successful exploit could allow the attacker to access sensitive information, including incoming and outgoing call records. Note: Web Access is disabled by default.

A vulnerability in the web UI of Cisco Desk Phone 9800 Series, Cisco IP Phone 6800, 7800, and 8800 Series, and Cisco Video Phone 8875 with Cisco Multiplatform Firmware could allow an authenticated, remote attacker to conduct stored cross-site scripting (XSS) attacks against users. This vulnerability exists because the web UI of an affected device does not properly validate user-supplied input. An attacker could exploit this vulnerability by injecting malicious code into specific pages of the interface. A successful exploit could allow the attacker to execute arbitrary script code in the context of the affected interface or access sensitive, browser-based information. Note: To exploit this vulnerability, Web Access must be enabled on the phone and the attacker must have Admin credentials on the device. Web Access is disabled by default.

A vulnerability in the directory permissions of Cisco Desk Phone 9800 Series, Cisco IP Phone 7800 and 8800 Series, and Cisco Video Phone 8875 could allow an unauthenticated, remote attacker to access sensitive information on an affected device. This vulnerability exists because the product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. An attacker could exploit this vulnerability by sending a crafted packet to the IP address of a device that has Web Access enabled. A successful exploit could allow the attacker to access sensitive information from the device. Note: To exploit this vulnerability, Web Access must be enabled on the phone. Web Access is disabled by default.

A vulnerability in the directory permissions of Cisco Desk Phone 9800 Series, Cisco IP Phone 7800 and 8800 Series, and Cisco Video Phone 8875 could allow an unauthenticated, remote attacker to write arbitrary files on an affected device. This vulnerability is due to a lack of proper authentication controls. An attacker could exploit this vulnerability by sending a crafted request to an affected device. A successful exploit could allow the attacker to perform arbitrary file writes to specific directories in the underlying operating system. Note: To exploit this vulnerability, Web Access must be enabled on the phone. Web Access is disabled by default.

Multiple vulnerabilities in Cisco Desk Phone 9800 Series, Cisco IP Phone 7800 and 8800 Series, and Cisco Video Phone 8875 running Cisco Session Initiation Protocol (SIP) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition or conduct a cross-site

A vulnerability in the Session Initiation Protocol (SIP) call-handling functionality of Cisco IP Phone 7800 Series phones and Cisco IP Phone 8800 Series phones could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected phone. The vulnerability is due to incomplete input validation of SIP Session Description Protocol (SDP) parameters by the SDP parser of an affected phone. An attacker could exploit this vulnerability by sending a malformed SIP packet to an affected phone. A successful exploit could allow the attacker to cause all active phone calls on the affected phone to be dropped while the SIP process on the phone unexpectedly restarts, resulting in a DoS condition. Cisco Bug IDs: CSCvf40066.

A vulnerability in the Cisco Discovery Protocol or Link Layer Discovery Protocol (LLDP) implementation for the Cisco IP Phone 7800 and 8800 Series could allow an unauthenticated, adjacent attacker to cause an affected phone to reload unexpectedly, resulting in a temporary denial of service (DoS) condition. The vulnerability is due to missing length validation of certain Cisco Discovery Protocol or LLDP packet header fields. An attacker could exploit this vulnerability by sending a malicious Cisco Discovery Protocol or LLDP packet to the targeted phone. A successful exploit could allow the attacker to cause the affected phone to reload unexpectedly, resulting in a temporary DoS condition. Versions prior to 12.6(1)MN80 are affected.

A vulnerability in the web-based management interface of Session Initiation Protocol (SIP) Software for Cisco IP Phone 8800 Series could allow an authenticated, remote attacker to write arbitrary files to the filesystem. The vulnerability is due to insufficient input validation and file-level permissions. An attacker could exploit this vulnerability by uploading invalid files to an affected device. A successful exploit could allow the attacker to write files in arbitrary locations on the filesystem. This vulnerability affects Cisco IP Phone 8800 Series products running a SIP Software release prior to 11.0(5) for Wireless IP Phone 8821 and 8821-EX; and 12.5(1)SR1 for the IP Conference Phone 8832 and the rest of the IP Phone 8800 Series.

A vulnerability in the web-based management interface of Session Initiation Protocol (SIP) Software for Cisco IP Phone 8800 Series could allow an unauthenticated, remote attacker to conduct a cross-site request forgery (CSRF) attack. The vulnerability is due to insufficient CSRF protections for the web-based management interface of an affected device. An attacker could exploit this vulnerability by persuading an authenticated user of the interface to follow a crafted link. A successful exploit could allow the attacker to perform arbitrary actions on a targeted device via a web browser and with the privileges of the user. This vulnerability affects Cisco IP Phone 8800 Series products running a SIP Software release prior to 11.0(5) for Wireless IP Phone 8821 and 8821-EX; and 12.5(1)SR1 for the IP Conference Phone 8832 and the rest of the IP Phone 8800 Series. Cisco IP Conference Phone 8831 is not affected.

A vulnerability in the web-based management interface of Session Initiation Protocol (SIP) Software for Cisco IP Phone 8800 Series could allow an unauthenticated, remote attacker to cause high disk utilization, resulting in a denial of service (DoS) condition. The vulnerability exists because the affected software does not restrict the maximum size of certain files that can be written to disk. An attacker who has valid administrator credentials for an affected system could exploit this vulnerability by sending a crafted, remote connection request to an affected system. A successful exploit could allow the attacker to write a file that consumes most of the available disk space on the system, causing application functions to operate abnormally and leading to a DoS condition. This vulnerability affects Cisco IP Phone 8800 Series products running a SIP Software release prior to 12.5(1)SR1.

A vulnerability in the web-based management interface of Session Initiation Protocol (SIP) Software for Cisco IP Phone 8800 Series could allow an unauthenticated, remote attacker to bypass authorization, access critical services, and cause a denial of service (DoS) condition. The vulnerability exists because the software fails to sanitize URLs before it handles requests. An attacker could exploit this vulnerability by submitting a crafted URL. A successful exploit could allow the attacker to gain unauthorized access to critical services and cause a DoS condition. This vulnerability affects Cisco IP Phone 8800 Series products running a SIP Software release prior to 11.0(5) for Wireless IP Phone 8821 and 8821-EX; and 12.5(1)SR1 for the IP Conference Phone 8832 and the rest of the IP Phone 8800 Series. Cisco IP Conference Phone 8831 is not affected.

A vulnerability in the web-based management interface of Session Initiation Protocol (SIP) Software for Cisco IP Phone 7800 Series and Cisco IP Phone 8800 Series could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition or execute arbitrary code. The vulnerability exists because the software improperly validates user-supplied input during user authentication. An attacker could exploit this vulnerability by connecting to an affected device using HTTP and supplying malicious user credentials. A successful exploit could allow the attacker to trigger a reload of an affected device, resulting in a DoS condition, or to execute arbitrary code with the privileges of the app user. Cisco fixed this vulnerability in the following SIP Software releases: 10.3(1)SR5 and later for Cisco Unified IP Conference Phone 8831; 11.0(4)SR3 and later for Cisco Wireless IP Phone 8821 and 8821-EX; and 12.5(1)SR1 and later for the rest of the Cisco IP Phone 7800 Series and 8800 Series.

Cross-site scripting (XSS) vulnerability on Cisco IP Phone 8800 devices with software 11.0 allows remote authenticated users to inject arbitrary web script or HTML via crafted parameters, aka Bug ID CSCuz03024.

Cisco IP Phone 8800 devices with software 11.0(1) allow remote attackers to cause a denial of service (memory corruption) via a crafted HTTP request, aka Bug ID CSCuz03038.

The license-certificate upload functionality on Cisco 8800 phones with software 11.0(1) allows remote authenticated users to delete arbitrary files via an invalid file, aka Bug ID CSCuz03010.

Cisco 8800 phones with software 11.0(1) do not properly enforce mounted-filesystem permissions, which allows local users to write to arbitrary files by leveraging shell access, aka Bug ID CSCuz03014.

A vulnerability in Session Initiation Protocol (SIP) call handling of Cisco IP Phone 8800 Series devices could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition due to the SIP process unexpectedly restarting. All active phone calls are dropped as the SIP process restarts. More Information: CSCvc29353. Known Affected Releases: 11.0(0.1). Known Fixed Releases: 11.0(0)MP2.153 11.0(0)MP2.62.

The TrustZone implementation in certain Broadcom MediaxChange firmware could allow an unauthenticated, physically proximate attacker to achieve arbitrary code execution in the TrustZone Trusted Execution Environment (TEE) of an affected device. This, for example, affects certain Cisco IP Phone and Wireless IP Phone products before 2021-07-07. Exploitation is possible only when the attacker can disassemble the device in order to control the voltage/current for chip pins.

A vulnerability in the web-based management interface of Cisco IP Phone 7800 and 8800 Series Phones could allow an unauthenticated, remote attacker to bypass authentication on an affected device. This vulnerability is due to insufficient validation of user-supplied input. An attacker could exploit this vulnerability by sending a crafted request to the web-based management interface. A successful exploit could allow the attacker to access certain parts of the web interface that would normally require authentication.