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CVE-2025-20350

Cisco Desk Phone 9800 Series, IP Phone 7800 and 8800 Series, and Video Phone 8875 with SIP Firmware Denial of Service Vulnerability

HIGH
7.5
CVSS Score
Published: October 15, 2025 at 04:15 PM UTC
Updated: October 8, 2026 at 11:10 AM UTC
17 products affected across 1 vendorIP Phone 8861 FirmwareIP Phone 8865 FirmwareIP Phone 8811 Firmware· also runs on 17 platforms

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Severity
HIGH7.5
Exploit prediction
EPSS 0.5%
SSVC
No known exploit

Description

A vulnerability in the web UI of Cisco Desk Phone 9800 Series, Cisco IP Phone 7800 and 8800 Series, and Cisco Video Phone 8875 running Cisco SIP Software could allow an unauthenticated, remote attacker to cause a DoS condition on an affected device. This vulnerability is due to a buffer overflow when an affected device processes HTTP packets. An attacker could exploit this vulnerability by sending crafted HTTP input to the device. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition. Note: To exploit this vulnerability, the phone must be registered to Cisco Unified Communications Manager and have Web Access enabled. Web Access is disabled by default.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Desk Phone 9841 Firmware· Cisco
95%
3.0\(1\) ≤ v ≤ 3.2\(1\)*
cisco-desk-phone-9841 (same device)
Desk Phone 9851 Firmware· Cisco
95%
3.0\(1\) ≤ v ≤ 3.2\(1\)*
cisco-desk-phone-9851 (same device)
Desk Phone 9861 Firmware· Cisco
95%
3.0\(1\) ≤ v ≤ 3.2\(1\)*
cisco-desk-phone-9861 (same device)
Desk Phone 9871 Firmware· Cisco
95%
3.0\(1\) ≤ v ≤ 3.2\(1\)*
cisco-desk-phone-9871 (same device)
IP Phone 7811 Firmware· Cisco
95%
v < 14.3\(1\)*14.3(1)14.3(1) sr114.3\(1\)
Affected range stops below 14.3(1), so it looks safe — our inference, not a vendor statement
cisco-ip-phone-7811 (same device)
IP Phone 7821 Firmware· Cisco
95%
v < 14.3\(1\)*14.3(1)14.3(1) sr114.3\(1\)
Affected range stops below 14.3(1), so it looks safe — our inference, not a vendor statement
cisco-ip-phone-7821 (same device)
IP Phone 7841 Firmware· Cisco
95%
v < 14.3\(1\)*14.3(1)14.3(1) sr114.3\(1\)
Affected range stops below 14.3(1), so it looks safe — our inference, not a vendor statement
cisco-ip-phone-7841 (same device)
IP Phone 7861 Firmware· Cisco
95%
v < 14.3\(1\)*14.3(1)14.3(1) sr114.3\(1\)
Affected range stops below 14.3(1), so it looks safe — our inference, not a vendor statement
cisco-ip-phone-7861 (same device)
IP Phone 8811 Firmware· Cisco
95%
v < 14.3\(1\)*14.3(1)14.3(1) sr114.3\(1\)
Affected range stops below 14.3(1), so it looks safe — our inference, not a vendor statement
cisco-ip-phone-8811 (same device)
IP Phone 8821 Firmware· Cisco
95%
v < 11.0\(1\)*11.0(0.7) mpp11.0(1)11.0(2)11.0(2) sr111.0(2) sr211.0(3)11.0(3) sr111.0(3) sr211.0(3) sr311.0(3) sr411.0(3) sr511.0(3) sr611.0(4)11.0(4) sr111.0(4) sr211.0(4) sr311.0(5)11.0(5) sr111.0(5) sr211.0(5) sr311.0(6)11.0(6) sr111.0(6) sr211.0(6) sr411.0(6) sr511.0(6) sr611.0\(0.7\)11.0\(1\)11.0\(2\)11.0\(3\)11.0\(4\)11.0\(5\)11.0\(6\)
Affected range stops below 11.0(1), so it looks safe — our inference, not a vendor statement
cisco-ip-phone-8821 (same device)

Runs on — not affected

The affected product only carries this flaw when running on these platforms. The platforms themselves are not vulnerable.

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (1)

Vendor Advisory
Source: cverecord
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-phone-dos-FPyjLV7A

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGHcisco
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-121

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