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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 3 May 2022.
Ip Phone 8865 FirmwareOperating system · Cisco

CVE-2020-3161

CRITICAL · 9.8 CVSS v3.1 Published 2020-04-15
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
In the wild High EPSS Public exploit Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
A vulnerability in the web server for Cisco IP Phones could allow an unauthenticated, remote attacker to execute code with root privileges or cause a reload of an affected IP phone, resulting in a denial of service (DoS) condition. The vulnerability is due to a lack of proper input validation of HTTP requests. An attacker could exploit this vulnerability by sending a crafted HTTP request to the web server of a targeted device. A successful exploit could allow the attacker to remotely execute code with root privileges or cause a reload of an affected IP phone, resulting in a DoS condition.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A stack-based buffer overflow vulnerability in the embedded HTTP server of Cisco IP phones allows unauthenticated remote attackers to send specially crafted HTTP requests that overflow stack buffers, enabling either root-level code execution or device reload (DoS). The flaw stems from insufficient input validation on HTTP request parameters.

MitigationDisable the HTTP server on Cisco IP phones if not required for management, or apply Cisco's available firmware patches for affected IP phone models; verify phone functionality after updates.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Ip Phone 8865 FirmwareOperating system
Affected:= 10.3\(1\)es14= 11.0\(1\)= 11.0\(5\)sr1
Ip Phone 8851 FirmwareOperating system
Affected:= 10.3\(1\)es14= 11.0\(1\)= 11.0\(5\)sr1
Ip Phone 7841 FirmwareOperating system
Affected:= 11.0\(1\)
Ip Phone 7821 FirmwareOperating system
Affected:= 11.0\(1\)
Ip Phone 8811 FirmwareOperating system
Affected:= 10.3\(1\)es14= 11.0\(1\)= 11.0\(5\)sr1
Ip Phone 8861 FirmwareOperating system
Affected:= 10.3\(1\)es14= 11.0\(1\)= 11.0\(5\)sr1
Ip Phone 8845 FirmwareOperating system
Affected:= 10.3\(1\)es14= 11.0\(1\)= 11.0\(5\)sr1
Ip Phone 7861 FirmwareOperating system
Affected:= 11.0\(1\)

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify the phone model
    Check the physical label on the back of the phone or access the phone's web interface and look for the model number in the device information section
    Affected if The model is one of: 8865, 8851, 7841, 7821, 8811, 8861, 8845, or 7861
  2. Check the installed firmware version
    Access the phone web interface (navigate to the phone's IP address in a browser) and look in the Device Information or Status section for the firmware version, or check via the phone menu under Settings > Status > Firmware Version
    Affected if The firmware version equals 10.3(1)es14, 11.0(1), or 11.0(5)sr1
  3. Verify the web server is enabled
    Access the phone web interface and navigate to the web server settings section, or check the phone menu under Settings > Security Settings > Web Server. The web interface must be accessible over HTTP/HTTPS for the vulnerability to be exploitable
    Affected if The built-in web server is enabled and reachable (this is the default state on most Cisco IP phones)

You are affected if you have a Cisco IP Phone model 8865, 8851, 7841, 7821, 8811, 8861, 8845, or 7861 running firmware version 10.3(1)es14, 11.0(1), or 11.0(5)sr1 AND the web server feature is enabled on the device

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Disable the HTTP server on Cisco IP phones if not required for management, or apply Cisco's available firmware patches for affected IP phone models; verify phone functionality after updates.

Fix this in Ip Phone 8865 Firmware Exploited in the wild — priority engagement
  • Consultation4.0 h
  • Implementation6.0 h
  • Testing3.0 h
  • Review / QA2.0 h
15.0 hours of engineering $2,690
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2020-3161 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data