CVE-2023-20259Network attack vector

Unauthenticated service interruption via unvalidated API requests

Published Oct 4, 2023 · Updated Aug 2, 2024

Resource exhaustion in Cisco Unified Communications products allows remote attackers to interrupt call processing via crafted HTTP requests. An unauthenticated API endpoint accepts insufficiently validated requests that drive sustained CPU utilization and delay web management and user traffic. No credentials or special configuration are required; service recovers without manual intervention after the request stream stops.

CVSS severity8.6
High
EPSS probability0.61%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Resource exhaustion in Cisco Unified Communications products allows remote attackers to interrupt call processing via crafted HTTP requests. An unauthenticated API endpoint accepts insufficiently validated requests that drive sustained CPU utilization and delay web management and user traffic. No credentials or special configuration are required; service recovers without manual intervention after the request stream stops.

The record

CVE
CVE-2023-20259
Published
Oct 4, 2023
Updated
Aug 2, 2024
Vendor
ClamAV
Product
Cisco Emergency Responder
Classifications
CWE-400, T1499.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 4, 2023CVE publishedPublication date reported by the CVE source.
  2. Aug 2, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=12.5(1)SU7
  2. Affected versionversion=14
  3. Affected versionversion=14SU3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

ClamAV · Cisco Emergency Responderversion=12.5(1)SU7; version=14; version=14SU3
ClamAV · Cisco Prime Collaboration Deploymentversion=14SU3
ClamAV · Cisco Unified Communications Manager IM and Presence Serviceversion=12.5(1)SU7; version=14SU3
ClamAV · Cisco Unified Communications Managerversion=12.5(1)SU7; version=12.5(1)SU7a; version=14SU3
ClamAV · Cisco Unity Connectionversion=14SU3

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
8.6Cisco Systems, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
T1499.003Application Exhaustion Flood

Public exploit references

No public exploit references are available in this record.

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

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo