CVE-2026-2457Network attack vector

Authenticated impersonation via unsanitized post metadata

Published Mar 16, 2026 · Updated Mar 16, 2026

Origin validation error in affected Mattermost 10.11, 11.2, and 11.3 releases allows remote authenticated users to spoof permalink embeds. The post update API accepts client-supplied post metadata without sanitizing the user attribution rendered in a permalink embed. An authenticated account can send a crafted PUT request that makes an embed impersonate another user, affecting message integrity without reported data disclosure or service interruption.

CVSS severity4.3
Medium
EPSS probability0.11%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Origin validation error in affected Mattermost 10.11, 11.2, and 11.3 releases allows remote authenticated users to spoof permalink embeds. The post update API accepts client-supplied post metadata without sanitizing the user attribution rendered in a permalink embed. An authenticated account can send a crafted PUT request that makes an embed impersonate another user, affecting message integrity without reported data disclosure or service interruption.

The record

CVE
CVE-2026-2457
Published
Mar 16, 2026
Updated
Mar 16, 2026
Vendor
Mattermost
Product
Mattermost
Classifications
CWE-346, T1565.001
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 16, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 16, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=10.11.0 <=10.11.10
  2. Affected versionversion=11.2.0 <=11.2.2
  3. Affected versionversion=11.3.0 <=11.3.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Mattermost · Mattermostversion=10.11.0 <=10.11.10; version=11.2.0 <=11.2.2; version=11.3.0 <=11.3.0

Published CVSS scores

4.3Mattermost, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/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-346Origin Validation Error
T1565.001Stored Data Manipulation

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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo