CVE-2021-23155Network attack vector

Server impersonation via improper certificate-chain validation

Published Nov 18, 2021 · Updated Sep 17, 2024

Certificate-chain validation in Gallagher Command Centre Mobile Client before 8.60.065 allows man-in-the-middle attackers to impersonate the server. The cloud certificate-chain check fails to establish a trust path to the legitimate Command Centre Server before accepting the peer. An attacker able to intercept the client-server connection can present an untrusted chain and act as the server, exposing or altering security-management traffic and disrupting operations.

CVSS severity9.0
Critical
EPSS probability0.48%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Certificate-chain validation in Gallagher Command Centre Mobile Client before 8.60.065 allows man-in-the-middle attackers to impersonate the server. The cloud certificate-chain check fails to establish a trust path to the legitimate Command Centre Server before accepting the peer. An attacker able to intercept the client-server connection can present an untrusted chain and act as the server, exposing or altering security-management traffic and disrupting operations.

The record

CVE
CVE-2021-23155
Published
Nov 18, 2021
Updated
Sep 17, 2024
Vendor
Gallagher Security
Product
Command Centre Mobile App
Classifications
CWE-295, CWE-296, T1638
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 18, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 17, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=8.60 <8.60.065
  2. Affected versionversion=unspecified <=8.50

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Gallagher Security · Command Centre Mobile Appversion=8.60 <8.60.065; version=unspecified <=8.50

Published CVSS scores

6.8NIST NVDCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:N/A:N
9.0Gallagher Group Ltd.CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
4.3NIST NVDAV:N/AC:M/Au:N/C:P/I:N/A:N

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-295Improper Certificate Validation
CWE-296Improper Following of a Certificate's Chain of Trust
T1638Adversary-in-the-Middle

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

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Your stack

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