Vulnerability in Cisco Session Initiation Protocol (Sip) Software
CVE-2025-20335
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.
EPSS exploit prediction
EPSS: 0.004 (27.5th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 27th percentile — 27.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000
Affected products
- Cisco Session Initiation Protocol (Sip) Software — versions 12.1(1)SR1, 11.5(1), 10.3(2)
- Cisco Desk Phone 9841
- Cisco Desk Phone 9841 Firmware
- Cisco Desk Phone 9851
- Cisco Desk Phone 9851 Firmware
- Cisco Desk Phone 9861
- Cisco Desk Phone 9861 Firmware
- Cisco Desk Phone 9871
- Cisco Desk Phone 9871 Firmware
- Cisco Ip Phone 7811
Weakness classification (CWE)
Public proof-of-concept exploits
References
Frequently asked questions
- What is CVE-2025-20335?
- CVE-2025-20335 is a medium-severity vulnerability in Cisco Session Initiation Protocol (Sip) Software, classified under Improper Access Control. CVSS score: 5.3/10. Published 2025-09-03.
- How severe is CVE-2025-20335?
- Medium severity. CVSS v3 base score is 5.3 out of 10.
- Is CVE-2025-20335 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.