CVE-2023-5967Network attack vector

Authenticated Calls interruption via missing User-Agent handling

Published Nov 6, 2023 · Updated Sep 12, 2024

Improper request validation in affected Mattermost releases allows remote authenticated users to crash the Calls plugin over the network. The Calls request path fails to handle an absent User-Agent header and enters a panic instead of returning an error. A valid low-privilege account and a crafted plugin request without that header are required; the interruption is limited to Calls.

CVSS severity4.3
Medium
EPSS probability0.51%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper request validation in affected Mattermost releases allows remote authenticated users to crash the Calls plugin over the network. The Calls request path fails to handle an absent User-Agent header and enters a panic instead of returning an error. A valid low-privilege account and a crafted plugin request without that header are required; the interruption is limited to Calls.

The record

CVE
CVE-2023-5967
Published
Nov 6, 2023
Updated
Sep 12, 2024
Vendor
Mattermost
Product
Mattermost
Classifications
CWE-754, T1499.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Nov 6, 2023CVE publishedPublication date reported by the CVE source.
  2. Sep 12, 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=0 <=7.8.11
  2. Affected versionversion=0 <=8.0.3
  3. Affected versionversion=0 <=8.1.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Mattermost · Mattermostversion=0 <=7.8.11; version=0 <=8.0.3; version=0 <=8.1.2

Published CVSS scores

4.3Mattermost, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-754Improper Check for Unusual or Exceptional Conditions
T1499.004Application or System Exploitation

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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