CVE-2023-3581

WebSocket API access via permissive HTTPS origins

Published Jul 17, 2023 · Updated Oct 30, 2024

Origin validation error in Mattermost 7.8, 7.9, and 7.10 branches allows man-in-the-middle attackers to access WebSocket APIs. The server's WebSocket upgrade origin check accepts an HTTPS origin without requiring its host to match the configured Site URL or AllowCorsFrom list. The attacker must occupy a man-in-the-middle position, and successful abuse permits WebSocket API operations within the intercepted session.

CVSS severity6.2
Medium
EPSS probability0.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Origin validation error in Mattermost 7.8, 7.9, and 7.10 branches allows man-in-the-middle attackers to access WebSocket APIs. The server's WebSocket upgrade origin check accepts an HTTPS origin without requiring its host to match the configured Site URL or AllowCorsFrom list. The attacker must occupy a man-in-the-middle position, and successful abuse permits WebSocket API operations within the intercepted session.

The record

CVE
CVE-2023-3581
Published
Jul 17, 2023
Updated
Oct 30, 2024
Vendor
Mattermost
Product
Mattermost
Classifications
CWE-346, T1557
Attack vector
physical
Privileges
admin

Timeline

How it unfolded

  1. Jul 17, 2023CVE publishedPublication date reported by the CVE source.
  2. Oct 30, 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 <=7.10.2
  2. Affected versionversion=0 <=7.8.6
  3. Affected versionversion=0 <=7.9.4

What conditions does exploitation require?

Attack vectorphysical
Required privilegesadmin

What is affected?

Mattermost · Mattermostversion=0 <=7.10.2; version=0 <=7.8.6; version=0 <=7.9.4

Published CVSS scores

8.1NIST NVDCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
6.2Mattermost, Inc.CVSS:3.1/AV:P/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorphysical
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-346Origin Validation Error
T1557Adversary-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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