CVE-2020-3161Known exploitationPublic exploitNetwork attack vector

Root code execution via unchecked URI formatting

Published Apr 15, 2020 · Updated Oct 21, 2025

Stack-based buffer overflow in Cisco IP Phone firmware allows remote attackers to execute code as root or reload a phone via crafted HTTP. The /deviceconfig/setActivationCode handler in libHTTPService.so passes an unchecked parameter string to sprintf when constructing a URI, overflowing a stack buffer. The affected firmware is exposed only when web access is enabled, a setting disabled by default; successful exploitation grants root execution or forces a device reload.

CVSS severity9.8
Critical
EPSS probability83.86%
Next 30 days · Sep 16, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stack-based buffer overflow in Cisco IP Phone firmware allows remote attackers to execute code as root or reload a phone via crafted HTTP. The /deviceconfig/setActivationCode handler in libHTTPService.so passes an unchecked parameter string to sprintf when constructing a URI, overflowing a stack buffer. The affected firmware is exposed only when web access is enabled, a setting disabled by default; successful exploitation grants root execution or forces a device reload.

The record

CVE
CVE-2020-3161
Published
Apr 15, 2020
Updated
Oct 21, 2025
Vendor
Cisco
Product
Cisco IP Phone
Classifications
CWE-20, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 15, 2020CVE publishedPublication date reported by the CVE source.
  2. Oct 21, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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  1. Affected versionversion=n/a

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Cisco · Cisco IP Phoneversion=n/a

Published CVSS scores

10.0TenableAV:N/AC:L/Au:N/C:C/I:C/A:C
9.8Cisco Systems, Inc.CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:X/RL:X/RC:X

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationReported
Public exploitPublished

Weakness, pattern, technique

CWE-20Improper Input Validation
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Reported exploitation

Technologies

Your stack

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Your stack

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