Cisco Security Advisory
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CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N/E:X/RL:X/RC:X
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Multiple vulnerabilities in the directory permissions of Cisco Desk Phone 9800 Series, Cisco IP Phone 7800 and 8800 Series, and Cisco Video Phone 8875 with Cisco Session Initiation Protocol (SIP) Software could allow an unauthenticated, remote attacker to conduct arbitrary file write and information disclosure attacks on an affected device.
Note: To exploit these vulnerabilities, Web Access must be enabled on the phone. Web Access is disabled by default.
For more information about these vulnerabilities, see the Details section of this advisory.
Cisco has released software updates that address these vulnerabilities. There are no workarounds that address these vulnerabilities.
This advisory is available at the following link:
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-phone-write-g3kcC5Df
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Vulnerable Products
At the time of publication, this vulnerability affected the following Cisco products if they were running a vulnerable release of Cisco SIP Phone Software and had Web Access enabled:
- Desk Phone 9800 Series
- IP Phone 7800 Series
- IP Phone 8800 Series
- Video Phone 8875
The Web Access feature is disabled by default.
For information about which Cisco software releases were vulnerable at the time of publication, see the Fixed Software section of this advisory. See the Details section in the bug ID(s) at the top of this advisory for the most complete and current information.
Determine Whether Web Access Is Enabled
Web Access is disabled by default on Cisco phones. If a user can browse to the IP address listed in the phone configuration by following these steps, Web Access has been enabled:
- Choose the gear icon on the front of the phone to access the phone configuration and determine the IP address of the phone.
- Choose Admin settings > Network Setup > Ethernet setup or Wi-Fi client setup > IPv4 setup.
- Type the IP address in a browser window and click Enter.
If the Device Information screen is displayed, then Web Access is enabled on the phone.
To enable or disable Web Access, follow these steps:
- Log in to the Communications Manager to which the phone is registered using Admin privileges, which allow modification of devices.
- Choose Device > Phone.
- Type in the search criteria and choose Find.
- Choose the appropriate device from the Device Name list.
- Scroll down to Web Access, toggle between Enabled or Disabled as desired, and click Save.
- Verify that the desired state has been set by typing the IP address into a browser window and clicking Enter.
Products Confirmed Not Vulnerable
Only products listed in the Vulnerable Products section of this advisory are known to be affected by these vulnerabilities.
Cisco has confirmed that this vulnerability does not affect Cisco IP Phone 7800 or 8800 Series Phones that are running Cisco Multiplatform Firmware.
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The vulnerabilities are not dependent on one another. Exploitation of one of the vulnerabilities is not required to exploit the other vulnerability. In addition, a software release that is affected by one of the vulnerabilities may not be affected by the other vulnerability.
Details about the vulnerabilities are as follows:
CVE-2025-20335: Cisco Desk Phone 9800 Series, IP Phone 7800 and 8800 Series, and Video Phone 8875 with SIP Software Arbitrary File Write Vulnerability
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.
Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.
Bug ID(s): CSCwn51679, CSCwn55709, CSCwn55710, CSCwn55712, CSCwn55714, CSCwn55725, CSCwn55726, CSCwn55727, CSCwn55728
CVE ID: CVE-2025-20335
Security Impact Rating (SIR): Medium
CVSS Base Score: 5.3
CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:NCVE-2025-20336: Cisco Desk Phone 9800 Series, IP Phone 7800 and 8800 Series, and Video Phone 8875 with SIP Software Information Disclosure Vulnerability
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.
Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.
Bug ID(s): CSCwn51677, CSCwn52909, CSCwn52910, CSCwn52911, CSCwn52913, CSCwn52919, CSCwn52920, CSCwn52921, CSCwn52922
CVE ID: CVE-2025-20336
Security Impact Rating (SIR): Medium
CVSS Base Score: 5.3
CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
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There are no workarounds that address these vulnerabilities.
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When considering software upgrades, customers are advised to regularly consult the advisories for Cisco products, which are available from the Cisco Security Advisories page, to determine exposure and a complete upgrade solution.
In all cases, customers should ensure that the devices to be upgraded contain sufficient memory and confirm that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, customers are advised to contact the Cisco Technical Assistance Center (TAC) or their contracted maintenance providers.
Fixed Releases
At the time of publication, the release information in the following tables was accurate. See the Details section in the bug ID(s) at the top of this advisory for the most complete and current information.
The left column lists Cisco software releases, and the right column indicates whether a release was affected by the vulnerabilities that are described in this advisory and which release included the fix for these vulnerabilities.
Desk Phone 9800 Series
Cisco SIP Software Release First Fixed Release 3 3.3(1) IP Phone 7800 and 8800 Series
Cisco SIP Software Release First Fixed Release Earlier than 14.3 Migrate to a fixed release. 14.3 14.3(1)SR2 IP Phone 8821
Cisco SIP Software Release First Fixed Release Earlier than 11 Migrate to a fixed release. 11 11.0(6)SR7 Video Phone 8875
Cisco SIP Software Release First Fixed Release 2.3(1)SR1 and earlier Migrate to a fixed release. 3 3.3(1) The Cisco Product Security Incident Response Team (PSIRT) validates only the affected and fixed release information that is documented in this advisory.
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The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.
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CVE-2025-20335: This vulnerability was found during internal security testing by Kent Yoder of the Cisco Advanced Security Initiatives Group (ASIG).
CVE-2025-20336: This vulnerability was found during internal security testing by Zach Sanchez of the Cisco ASIG.
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To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.
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Show LessVersion Description Section Status Date 1.0 Initial public release. — Final 2025-SEP-03
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