CVE-2023-20259: A vulnerability in an API endpoint of multiple Cisco Unified Communications Products could allow an unauthenti

This month

HIGH 8.6REMOTEDOWNGRADEDOWNGRADEMITIGATE

CVE-2023-20259 is a high-severity flaw (CVSS 8.6) affecting emergency responder, prime collaboration deployment, unified communications manager. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A vulnerability in an API endpoint of multiple Cisco Unified Communications Products could allow an unauthenticated, remote attacker to cause high CPU utilization, which could impact access to the web-based management interface and cause delays with call processing. This API is not used for device management and is unlikely to be used in normal operations of the device. This vulnerability is due to improper API authentication and incomplete va

Why this priority

High severity
Remotely exploitable, no login, no user action

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	8.6 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.8% (top 43%)
CISA exploited list	No
Weakness	CWE-400
Published	2023-10-04
Last modified	2026-06-17

Publisher (CNA): Cisco Systems, Inc. · Vendor: cisco

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2023-10-04 17:15 UTCPublished CVE record published
2026-06-17 05:30 UTCUpdated Record last modified

cisco emergency responder DOWNGRADE

Affected: 14su3

Fixed in: no fixed release known

Safe to downgrade to: a release before 14su3

1. Check installed version

apt-cache policy emergency-responder || rpm -q emergency-responder || emergency-responder --version

2. No fixed release: DOWNGRADE to a release before 14su3 (Debian / Ubuntu)

apt-cache madison emergency-responder sudo apt install emergency-responder=<VERSION_BEFORE_14su3> sudo apt-mark hold emergency-responder

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list emergency-responder sudo dnf downgrade emergency-responder-<VERSION_BEFORE_14su3> sudo dnf versionlock add emergency-responder

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

cisco prime collaboration deployment DOWNGRADE

Affected: 14su3

Fixed in: no fixed release known

Safe to downgrade to: a release before 14su3

1. Check installed version

apt-cache policy prime-collaboration-deployment || rpm -q prime-collaboration-deployment || prime-collaboration-deployment --version

2. No fixed release: DOWNGRADE to a release before 14su3 (Debian / Ubuntu)

apt-cache madison prime-collaboration-deployment sudo apt install prime-collaboration-deployment=<VERSION_BEFORE_14su3> sudo apt-mark hold prime-collaboration-deployment

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list prime-collaboration-deployment sudo dnf downgrade prime-collaboration-deployment-<VERSION_BEFORE_14su3> sudo dnf versionlock add prime-collaboration-deployment

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

cisco unified communications manager MITIGATE

Affected: 12.5\(1\)su7 · 14su3

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy unified-communications-manager || rpm -q unified-communications-manager || unified-communications-manager --version

No fixed or unaffected release known

Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.

cisco unified communications manager im \& presence service MITIGATE

Affected: 12.5\(1\)su7 · 14su3

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy unified-communications-manager-im--presence-service || rpm -q unified-communications-manager-im--presence-service || unified-communications-manager-im--presence-service --version

No fixed or unaffected release known

Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.

cisco unity connection DOWNGRADE

Affected: 14su3

Fixed in: no fixed release known

Safe to downgrade to: a release before 14su3

1. Check installed version

apt-cache policy unity-connection || rpm -q unity-connection || unity-connection --version

2. No fixed release: DOWNGRADE to a release before 14su3 (Debian / Ubuntu)

apt-cache madison unity-connection sudo apt install unity-connection=<VERSION_BEFORE_14su3> sudo apt-mark hold unity-connection

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list unity-connection sudo dnf downgrade unity-connection-<VERSION_BEFORE_14su3> sudo dnf versionlock add unity-connection

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2023-20259?

emergency responder: downgrade or apply the listed mitigation; prime collaboration deployment: downgrade or apply the listed mitigation; unified communications manager: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2023-20259 being exploited?

CVE-2023-20259 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2023-20259 affect?

CVE-2023-20259 affects emergency responder, prime collaboration deployment, unified communications manager. Severity is high (CVSS 8.6). A vulnerability in an API endpoint of multiple Cisco Unified Communications Products could allow an unauthenticated, remote attacker to cause high CPU utilization, which could impact access to the web-based management interface and cause de

How urgent is CVE-2023-20259?

Priority 49/100. High severity; Remotely exploitable, no login, no user action

Software pages

Cisco vulnerabilities · Unity vulnerabilities

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References

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