GO-2026-4916 Mattermost doesn't rate limit login requests, allowing DoS in github.com/mattermost/mattermost-server

Mattermost doesn't rate limit login requests, allowing DoS in github.com/mattermost/mattermost-server. NOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions. If this is causing false-positive reports from...

PT-2026-29956

Mattermost doesn't rate limit login requests, allowing DoS in github.com/mattermost/mattermost-server. NOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions. If this is causing false-positive reports from...

GO-2026-4726 Mattermost fails to limit the size of responses from integration action endpoints in github.com/mattermost/mattermost-server

Mattermost fails to limit the size of responses from integration action endpoints in github.com/mattermost/mattermost-server. NOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions. If this is causing...

GO-2026-4725 Mattermost fails to properly validate User-Agent header tokens in github.com/mattermost/mattermost-server

Mattermost fails to properly validate User-Agent header tokens in github.com/mattermost/mattermost-server. NOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions. If this is causing false-positive reports from...

Incorrect Implementation of Authentication Algorithm

Overview github.com/mattermost/mattermost-server is an open source Slack-alternative in Golang and React. Affected versions of this package are vulnerable to Incorrect Implementation of Authentication Algorithm in the IsSameUser function. An attacker can gain unauthorized access to arbitrary user...

GO-2026-4786 Mattermost fails to validate user's authentication method when processing account auth type switch in github.com/mattermost/mattermost-server

Mattermost fails to validate user's authentication method when processing account auth type switch in github.com/mattermost/mattermost-server. NOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions. If this is...

GO-2026-4729 Mattermost allows a removed team member to enumerate all public channels within a private team in github.com/mattermost/mattermost-server

Mattermost allows a removed team member to enumerate all public channels within a private team in github.com/mattermost/mattermost-server. NOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions. If this is causi...

GO-2026-4749 Mattermost fails to validate team-specific upload_file permissions in github.com/mattermost/mattermost-server

Mattermost fails to validate team-specific uploadfile permissions in github.com/mattermost/mattermost-server. NOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions. If this is causing false-positive reports fro...

GO-2026-4727 Mattermost fails to bound memory allocation when processing PSD image files in github.com/mattermost/mattermost-server

Mattermost fails to bound memory allocation when processing PSD image files in github.com/mattermost/mattermost-server. NOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions. If this is causing false-positive...

GO-2026-4746 Mattermost fails to canonicalize IPv4-mapped IPv6 addresses before reserved IP validation in github.com/mattermost/mattermost-server

Mattermost fails to canonicalize IPv4-mapped IPv6 addresses before reserved IP validation in github.com/mattermost/mattermost-server. NOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions. If this is causing...

GO-2026-4733 Mattermost fails to bound memory allocation when processing DOC files in github.com/mattermost/mattermost-server

Mattermost fails to bound memory allocation when processing DOC files in github.com/mattermost/mattermost-server. NOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions. If this is causing false-positive reports...

GO-2026-4732 Mattermost allows attackers to spoof permalink embeds in github.com/mattermost/mattermost-server

Mattermost allows attackers to spoof permalink embeds in github.com/mattermost/mattermost-server. NOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions. If this is causing false-positive reports from...

GO-2026-4735 Mattermost fails to filter invite IDs based on user permissions in github.com/mattermost/mattermost-server

Mattermost fails to filter invite IDs based on user permissions in github.com/mattermost/mattermost-server. NOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions. If this is causing false-positive reports from...

GO-2026-4734 Mattermost fails to preserve the redacted state of burn-on-read posts during deletion in github.com/mattermost/mattermost-server

Mattermost fails to preserve the redacted state of burn-on-read posts during deletion in github.com/mattermost/mattermost-server. NOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions. If this is causing...

GO-2026-4745 Mattermost fails to properly enforce read permissions in search API endpoints in github.com/mattermost/mattermost-server

Mattermost fails to properly enforce read permissions in search API endpoints in github.com/mattermost/mattermost-server. NOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions. If this is causing false-positive...

Incorrect Authorization

Overview Affected versions of this package are vulnerable to Incorrect Authorization due to insufficient validation of permission requirements in the team member roles API endpoint. An attacker can gain unauthorized privilege to demote users to guest status by exploiting this flaw while...

CVE-2026-1629

A missing cache invalidation flaw has been discovered in mattermost server. Affected versions fail to invalidate cached permalink preview data when a user loses channel access which allows the user to continue viewing private channel content via previously cached permalink previews until cache...

CVE-2026-2454

A denial of service flaw has been discovered in mattermost server. Affected versions fail to handle incorrectly reported array lengths which allows malicious user to cause OOM errors and crash the server via sending corrupted msgpack frames within websocket messages to calls plugin. Mitigation...

CVE-2026-26230

A permissions validation flaw has been discovered in mattermost server. Affected versions fail to properly validate permission requirements in the team member roles API endpoint which allows team administrators to demote members to guest role. Mitigation Mitigation for this issue is either not...

CVE-2026-25780

A memory exhaustion flaw has been discovered in the Mattermost server. Affected versions fail to bound memory allocation when processing DOC files which allows an authenticated attacker to cause server memory exhaustion and denial of service via uploading a specially crafted DOC file. Mitigation...