Replayable timestamp bypass in Mattermost Plugins <=11.4 corrupts Zoom meetings
CVE-2026-3109 Published on March 26, 2026

Missing timestamp validation in Zoom webhook handler
Mattermost Plugins versions <=11.4 10.11.11.0 fail to validate webhook request timestamps which allows an attacker to corrupt Zoom meeting state in Mattermost via replayed webhook requests. Mattermost Advisory ID: MMSA-2026-00584

Vendor Advisory NVD

Vulnerability Analysis

CVE-2026-3109 can be exploited with network access, and requires user privileges. This vulnerability is consided to have a high level of attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity, and a small impact on availability.

Attack Vector:
NETWORK
Attack Complexity:
HIGH
Privileges Required:
HIGH
User Interaction:
NONE
Scope:
UNCHANGED
Confidentiality Impact:
NONE
Integrity Impact:
NONE
Availability Impact:
LOW

Weakness Type

Improper Check for Unusual or Exceptional Conditions

The software does not check or incorrectly checks for unusual or exceptional conditions that are not expected to occur frequently during day to day operation of the software.


Products Associated with CVE-2026-3109

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MatterMost
 

Affected Versions

Mattermost:

Exploit Probability

EPSS
0.04%
Percentile
10.48%

EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.