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Vulnerabilities

Vulnerability · CVE-2020-3161

Cisco IP Phones Web Server Remote Code Execution and Denial-of-Service Vulnerability

Published Apr 15, 2020 · catalog updated Jun 16, 2026 · Cisco Cisco IP Phones

Patch now

CVE-2020-3161 is in the CISA known-exploited catalog, due May 3, 2022. Confirm Cisco Cisco IP Phones against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Severity
Critical9.8
Known exploitation
CISA KEV and VulnCheck KEV
EPSS
83.86%
Remediation
Remediation guidance
Affected products
cpe cisco/ip phone 7821 firmware · cpe cisco/ip phone 7841 firmware · cpe cisco/ip phone 7861 firmware · cpe cisco/ip phone 8811 firmware · cpe cisco/ip phone 8845 firmware · cpe cisco/ip phone 8851 firmware

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe cisco/ip phone 7821 firmware11.0\(1\)
  • cpe cisco/ip phone 7841 firmware11.0\(1\)
  • cpe cisco/ip phone 7861 firmware11.0\(1\)
  • cpe cisco/ip phone 8811 firmware10.3\(1\)es14
  • cpe cisco/ip phone 8845 firmware10.3\(1\)es14
  • cpe cisco/ip phone 8851 firmware10.3\(1\)es14
  • cpe cisco/ip phone 8851 firmware11.0\(1\)
  • cpe cisco/ip phone 8851 firmware11.0\(5\)sr1
  • cpe cisco/ip phone 8861 firmware10.3\(1\)es14
  • cpe cisco/ip phone 8865 firmware10.3\(1\)es14
  • cpe cisco/ip phone 8865 firmware11.0\(1\)
  • cpe cisco/ip phone 8865 firmware11.0\(5\)sr1
  • vendor Cisco Cisco IP Phonesversion unspecified

How to fix CVE-2020-3161

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

CVE-2020-3161 is in the CISA known-exploited catalog, due May 3, 2022. Confirm Cisco Cisco IP Phones against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Which versions are affected?

Compare what you have installed with cisco/ip phone 7821 firmware 11.0\(1\); cisco/ip phone 7841 firmware 11.0\(1\); cisco/ip phone 7861 firmware 11.0\(1\); cisco/ip phone 8811 firmware 10.3\(1\)es14. Apply updates per vendor instructions.

What should an analyst verify?

CWE-20: Improper Input Validation. EPSS 83.86%. The CISA KEV listing is the exploitation evidence. A public exploit reference is linked in Sources. That is not the same as confirmed exploitation. Use the source links for the original advisory.

Technology hubs

Cisco security

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Apr 15, 2020 · Catalog

    Detected

    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 we

  2. Nov 3, 2021 · CISA KEV

    Known exploited

    Apply updates per vendor instructions.

  3. May 3, 2022 · CISA KEV

    Remediation due

    Apply updates per vendor instructions.

  4. Jun 16, 2026 · Catalog

    Updated

    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 we

Sources

  • CISA KEVConfirmed exploitationCVE-2020-3161

    Cisco IP Phones contain an improper input validation vulnerability for HTTP requests. Exploitation could allow an attacker to execute code remotely with root privileges or cause a denial-of-service (DoS) condition.

    cisa.gov
  • CVE.orgVulnerability recordCVE-2020-3161

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2020-3161

    30-day exploitation probability 83.9%

    first.org
  • Exploit DatabasePublic exploit reference48342

    Public archive entry. The exploit body is not stored here.

    exploit-db.com
  • NIST NVDVulnerability recordCVE-2020-3161

    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 inp

    nvd.nist.gov
  • Packet Storm SecurityCited referencehttp://packetstormsecurity.com/files/157265/Cisco-IP-Phone-11.7-Denial-Of-Service.html

    Packet Storm link already published on the finding.

    packetstormsecurity.com
  • VulnCheck KEVConfirmed exploitationCVE-2020-3161

    Cisco IP Phones contain an improper input validation vulnerability for HTTP requests. Exploitation could allow an attacker to execute code remotely with root privileges or cause a denial-of-service (DoS) condition.

    vulncheck.com

References

Freshness

Last verified in this catalog Oct 17, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.