CVE-2025-20335 Missing authorization in Cisco Session Initiation Protocol (SIP) Software
Unauthenticated remote attackers can write arbitrary files to Cisco IP phones if Web Access is enabled, potentially compromising device integrity.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2025-20335?
CVE-2025-20335 is a medium-severity missing authorization vulnerability in Cisco Session Initiation Protocol (SIP) Software, published on 3 Sep 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-284
Which versions are affected by CVE-2025-20335?
It affects 17 products.
Products include Cisco Desk Phone 9841 Firmware, Cisco Desk Phone 9851 Firmware, Cisco Desk Phone 9861 Firmware, Cisco Desk Phone 9871 Firmware, Cisco Ip Phone 7811 Firmware, Cisco Ip Phone 7821 Firmware and 11 more.
How do I fix CVE-2025-20335?
No fix has been published for CVE-2025-20335 yet. Limit exposure of the affected software until one is available.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2025-20335 being exploited?
There is no known exploitation of CVE-2025-20335 in the wild and no public exploit code.
Other vulnerabilities in Cisco Session Initiation Protocol (SIP) Software
- CVE-2025-20350 Memory corruption in Cisco Session Initiation Protocol (SIP) Software
- CVE-2025-20351 Cross-site scripting in Cisco Session Initiation Protocol (SIP) Software
- CVE-2025-20336 Information disclosure in Cisco Session Initiation Protocol (SIP) Software
- CVE-2024-20445 Cisco IP Phone 7800, 8800, and 9800 Series Information Disclosure Vulnerability
- CVE-2025-20158 Cisco Video Phone 8875 and Desk Phone 9800 Series Information Disclosure Vulnerability
Sources
Also known as GHSA-8v48-phm3-pw95.