CVE-2026-6346Network attack vector

Credential disclosure via unsanitized support packet fields

Published May 18, 2026 · Updated May 18, 2026

Information disclosure in Mattermost 10.11.0 through 10.11.13, 11.4.0 through 11.4.3, and 11.5.0 through 11.5.1 exposes credentials. The support-packet generator copies sensitive configuration fields into the downloadable packet without sanitizing their plaintext values. Reachability requires System Admin access to generate and download a packet, or access to an existing packet containing the exposed credentials.

CVSS severity8.7
High
EPSS probability0.30%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in Mattermost 10.11.0 through 10.11.13, 11.4.0 through 11.4.3, and 11.5.0 through 11.5.1 exposes credentials. The support-packet generator copies sensitive configuration fields into the downloadable packet without sanitizing their plaintext values. Reachability requires System Admin access to generate and download a packet, or access to an existing packet containing the exposed credentials.

The record

CVE
CVE-2026-6346
Published
May 18, 2026
Updated
May 18, 2026
Vendor
Mattermost
Product
Mattermost
Classifications
CWE-200, T1552.001
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. May 18, 2026CVE publishedPublication date reported by the CVE source.
  2. May 18, 2026Record 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=10.11.0 <=10.11.13
  2. Affected versionversion=11.4.0 <=11.4.3
  3. Affected versionversion=11.5.0 <=11.5.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

Mattermost · Mattermostversion=10.11.0 <=10.11.13; version=11.4.0 <=11.4.3; version=11.5.0 <=11.5.1

Published CVSS scores

8.7Mattermost, Inc.CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-200Exposure of Sensitive Information to an Unauthorized Actor
T1552.001Unsecured Credentials: Credentials In Files

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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