No exploitation reportedFix available

CVE-2020-12456

Q: Is CVE-2020-12456 actively exploited?

Active exploitation of CVE-2020-12456 has not been confirmed. Its EPSS score was 3.1% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2020-12456?

CVE-2020-12456 has a CVSS v3 base score of 8.8 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

No exploitation reported by the sources we read.

Published2020-08-26
Fixed in214.100.1223.0
WeaknessCWE-22

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

A remote code execution vulnerability in Mitel MiVoice Connect Client before 214.100.1223.0 could allow an attacker to execute arbitrary code in the chat notification window, due to improper rendering of chat messages. A successful exploit could allow an attacker to steal session cookies, perform directory traversal, and execute arbitrary scripts in the context of the Connect client.

Timeline

dates in UTC

2020-08-2619:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 18:48 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2020-12456?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2020-12456?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Mitel mivoice connect client

Branch	Affected	Fixed in	Source
214.100	< 214.100.1223.0	214.100.1223.0	NVD

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Update Mitel mivoice connect client to 214.100.1223.0

Advisories and patches

www.mitel.comVendor Advisory
www.mitel.comVendor Advisory

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

NVDCVSS 3.18.8read 2026-10-23
NVDCVSS 2.06.5read 2026-10-23
NVDweakness (CWE)CWE-22read 2026-10-23
FIRST EPSSEPSS score3.1 %2026-10-22

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Published: 2020-08-26
Last Modified: 2026-06-17
NVD status: Analyzed

Frequently asked questions

What is CVE-2020-12456?

Is CVE-2020-12456 actively exploited?

Active exploitation of CVE-2020-12456 has not been confirmed. Its EPSS score was 3.1% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2020-12456?

CVE-2020-12456 has a CVSS v3 base score of 8.8 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

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