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CVE-2020-3574

Cisco IP Phone TCP Packet Flood Denial of Service Vulnerability

HIGH
7.5
CVSS Score
Published: November 6, 2020 at 06:16 PM UTC
Updated: June 17, 2026 at 03:18 AM UTC
17 products affected across 1 vendorIP Phone 8861 FirmwareIP Phone 8811 FirmwareIP Phone 8841 Firmware

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Severity
HIGH7.5
Exploit prediction
EPSS 8%
SSVC
No known exploit

Description

A vulnerability in the TCP packet processing functionality of Cisco IP Phones could allow an unauthenticated, remote attacker to cause the phone to stop responding to incoming calls, drop connected calls, or unexpectedly reload. The vulnerability is due to insufficient TCP ingress packet rate limiting. An attacker could exploit this vulnerability by sending a high and sustained rate of crafted TCP traffic to the targeted device. A successful exploit could allow the attacker to impact operations of the phone or cause the phone to reload, leading to a denial of service (DoS) condition.

Affected

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

IP Dect 210 Firmware· Cisco
95%
v < 4.8.1
Affected range stops below 4.8.1, so it looks safe — our inference, not a vendor statement
cisco-ip-dect-210 (same device)
IP Dect 6825 Firmware· Cisco
95%
v < 4.8.1
Affected range stops below 4.8.1, so it looks safe — our inference, not a vendor statement
cisco-ip-dect-6825 (same device)
IP Phone 8811 Firmware· Cisco
95%
v < 11.3.2
Affected range stops below 11.3.2, so it looks safe — our inference, not a vendor statement
cisco-ip-phone-8811 (same device)
IP Phone 8841 Firmware· Cisco
95%
v < 11.3.2
Affected range stops below 11.3.2, so it looks safe — our inference, not a vendor statement
cisco-ip-phone-8841 (same device)
IP Phone 8851 Firmware· Cisco
95%
v < 11.3.2
Affected range stops below 11.3.2, so it looks safe — our inference, not a vendor statement
cisco-ip-phone-8851 (same device)
IP Phone 8861 Firmware· Cisco
95%
v < 11.3.2
Affected range stops below 11.3.2, so it looks safe — our inference, not a vendor statement
cisco-ip-phone-8861 (same device)
Unified IP Conference Phone 8831 Firmware· Cisco
95%
9.3(4) servicerelease3
cisco-unified-ip-conference-phone-8831 (same device)
Webex Room Phone Firmware· Cisco
95%
v < 1.2.0
Affected range stops below 1.2.0, so it looks safe — our inference, not a vendor statement
cisco-webex-room-phone (same device)
IP Phone Multiplatform Firmware· Cisco
60%
All versions
Ip Dect 210· Ciscodevice
80%
All versions

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 Advisoryx_refsource_CISCOPatch
Source: [email protected]
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-voip-phone-flood-dos-YnU9EXOv

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

StatusMODIFIED
CWE
CWE-371NVD-CWE-Other

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