CVE-2023-1777Network attack vector

Authenticated message disclosure via unchecked preview authorization

Published Mar 31, 2023 · Updated Dec 6, 2024

Information disclosure in Mattermost 6.3.0 through 7.8.0 allows remote authenticated users to read linked-message contents via createPost. The createPost API accepts a link to an existing message and returns its preview without enforcing the requester's access to that message. A valid account with permission to create a post is required; the result exposes message content outside the account's authorized channels.

CVSS severity6.5
Medium
EPSS probability0.54%
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 6.3.0 through 7.8.0 allows remote authenticated users to read linked-message contents via createPost. The createPost API accepts a link to an existing message and returns its preview without enforcing the requester's access to that message. A valid account with permission to create a post is required; the result exposes message content outside the account's authorized channels.

The record

CVE
CVE-2023-1777
Published
Mar 31, 2023
Updated
Dec 6, 2024
Vendor
Mattermost
Product
Mattermost
Classifications
CWE-668, CWE-200, T1213.005
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 31, 2023CVE publishedPublication date reported by the CVE source.
  2. Dec 6, 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=6.3.0 <=7.1.5
  2. Affected versionversion=6.3.0 <=7.7.1
  3. Affected versionversion=6.3.0 <=7.8.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Mattermost · Mattermostversion=6.3.0 <=7.1.5; version=6.3.0 <=7.7.1; version=6.3.0 <=7.8.0

Published CVSS scores

6.5Mattermost, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
5.3NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-668Exposure of Resource to Wrong Sphere
CWE-200Exposure of Sensitive Information to an Unauthorized Actor
T1213.005Messaging Applications

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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