CVE-2023-20266: A vulnerability in Cisco Emergency Responder, Cisco Unified Communications Manager (Unified CM), Cisco Unified

Routine

MEDIUM 6.5DOWNGRADEDOWNGRADEMITIGATE

CVE-2023-20266 is a medium-severity flaw (CVSS 6.5) affecting emergency responder, unified communications manager, unity connection. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A vulnerability in Cisco Emergency Responder, Cisco Unified Communications Manager (Unified CM), Cisco Unified Communications Manager Session Management Edition (Unified CM SME), and Cisco Unity Connection could allow an authenticated, remote attacker to elevate privileges to root on an affected device. This vulnerability exists because the application does not properly restrict the files that are being used for upgrades. An attacker could exp

Why this priority

No elevated risk signals yet

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

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	High
User interaction	None
EPSS exploit chance	0.5% (top 58%)
CISA exploited list	No
Weakness	CWE-347, CWE-269
Published	2023-08-30
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

2023-08-30 17:15 UTCPublished CVE record published
2026-06-17 05:30 UTCUpdated Record last modified

cisco emergency responder DOWNGRADE

Affected: 12.5.1su4 · 12.5.1su8a · 14su3

Fixed in: no fixed release known

Safe to downgrade to: a release before 12.5.1su4

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 12.5.1su4 (Debian / Ubuntu)

apt-cache madison emergency-responder sudo apt install emergency-responder=<VERSION_BEFORE_12.5.1su4> 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_12.5.1su4> 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 unified communications manager DOWNGRADE

Affected: 12.5.1su8

Fixed in: no fixed release known

Safe to downgrade to: a release before 12.5.1su8

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 12.5.1su8 (Debian / Ubuntu)

apt-cache madison unified-communications-manager sudo apt install unified-communications-manager=<VERSION_BEFORE_12.5.1su8> sudo apt-mark hold unified-communications-manager

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

dnf --showduplicates list unified-communications-manager sudo dnf downgrade unified-communications-manager-<VERSION_BEFORE_12.5.1su8> sudo dnf versionlock add unified-communications-manager

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 unity connection MITIGATE

Affected: 12.5\(1\)su6 · 12.5\(1\)su7 · 12.5\(1\)su8 · 14su2 · 14su3

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

1. Check installed version

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

No fixed or unaffected release known

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

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-2023-20266?

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

Is CVE-2023-20266 being exploited?

CVE-2023-20266 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-2023-20266 affect?

CVE-2023-20266 affects emergency responder, unified communications manager, unity connection. Severity is medium (CVSS 6.5). A vulnerability in Cisco Emergency Responder, Cisco Unified Communications Manager (Unified CM), Cisco Unified Communications Manager Session Management Edition (Unified CM SME), and Cisco Unity Connection could allow an authenticated, remo

How urgent is CVE-2023-20266?

Priority 33/100. No elevated risk signals yet.

Software pages

Cisco vulnerabilities · Unity vulnerabilities

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References

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