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Fencer Vulns
medium 5.3

CVE-2025-20335 json

Cisco Desk Phone 9800 Series, IP Phone 7800 and 8800 Series, and Video Phone 8875 with SIP Firmware Information Arbitrary File Write Vulnerability

published 2025-09-03 14 mo ago modified 2026-06-17 4 mo ago also EUVD-2025-26614

cvss
5.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 29%
public exploits
0
none known

Summary

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.

Patch / fix

  • cisco desk_phone_9841_firmware 3.3\(1\)
  • cisco desk_phone_9851_firmware 3.3\(1\)
  • cisco desk_phone_9861_firmware 3.3\(1\)
  • cisco desk_phone_9871_firmware 3.3\(1\)
  • cisco ip_phone_7811_firmware 14.3\(1\)
  • cisco ip_phone_7821_firmware 14.3\(1\)
  • cisco ip_phone_7841_firmware 14.3\(1\)
  • cisco ip_phone_7861_firmware 14.3\(1\)
  • cisco ip_phone_8811_firmware 14.3\(1\)
  • cisco ip_phone_8841_firmware 14.3\(1\)
  • cisco ip_phone_8845_firmware 14.3\(1\)
  • cisco ip_phone_8851_firmware 14.3\(1\)
  • cisco ip_phone_8851nr_firmware 14.3\(1\)
  • cisco ip_phone_8861_firmware 14.3\(1\)
  • cisco ip_phone_8865_firmware 14.3\(1\)
  • cisco video_phone_8875_firmware 2.3\(1\), 3.3\(1\)
  • cisco ip_phone_8821_firmware 11.0\(6\)

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
14 mo ago

Exploit prediction

0.35% chance of exploitation in the next 30 days, higher than 29% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Affected products

  • Cisco Cisco Session Initiation Protocol (SIP) Software

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.