Mattermost: >> Mattermost Server >> 4.1.0 Security Vulnerabilities
Mattermost Plugins versions <=11.3 11.0.3 11.2.2 10.10.11.0 fail to implement authorisation checks on comment block modifications, which allows an authorised attacker with editor permission to modify comments created by other board members. Mattermost Advisory ID: MMSA-2025-00559
CVSS Score
4.3
EPSS Score
0.002
Published
2026-03-16
Mattermost Plugin MSTeams versions <2.1.0 and Mattermost Server versions 10.5.x <=10.5.1 with the MS Teams plugin enabled fail to perform constant time comparison on a MSTeams plugin webhook secret which allows an attacker to retrieve the webhook secret of the MSTeams plugin via a timing attack during webhook secret comparison.
CVSS Score
5.3
EPSS Score
0.003
Published
2025-04-16
Mattermost fails to check the "invite_guest" permission when inviting guests of other teams to a team, allowing a member with permissions to add other members but not to add guests to add a guest to a team as long as the guest was already a guest in another team of the server
CVSS Score
4.3
EPSS Score
0.003
Published
2024-02-29
Mattermost fails to properly restrict the access of files attached to posts in an archived channel, resulting in members being able to access files of archived channels even if the “Allow users to view archived channels” option is disabled.
CVSS Score
3.1
EPSS Score
0.003
Published
2024-02-29
Mattermost fails to properly authorize the requests fetching team associated AD/LDAP groups, allowing a user to fetch details of AD/LDAP groups of a team that they are not a member of.
CVSS Score
4.3
EPSS Score
0.004
Published
2024-02-29
Mattermost fails to properly validate the length of the emoji value in the custom user status, allowing an attacker to send multiple times a very long string as an emoji value causing high resource consumption and possibly crashing the server.
CVSS Score
4.3
EPSS Score
0.007
Published
2024-02-29
Mattermost fails to check if compliance export is enabled when fetching posts of public channels allowing a user that is not a member of the public channel to fetch the posts, which will not be audited in the compliance export.
CVSS Score
4.3
EPSS Score
0.003
Published
2024-02-29
Mattermost fails to check if a custom emoji reaction exists when sending it to a post and to limit the amount of custom emojis allowed to be added in a post, allowing an attacker sending a huge amount of non-existent custom emojis in a post to crash the mobile app of a user seeing the post and to crash the server due to overloading when clients attempt to retrive the aforementioned post.
CVSS Score
4.3
EPSS Score
0.005
Published
2024-02-09
Mattermost Jira Plugin fails to protect against logout CSRF allowing an attacker to post a specially crafted message that would disconnect a user's Jira connection in Mattermost only by viewing the message.
CVSS Score
3.5
EPSS Score
0.002
Published
2024-02-09
Mattermost Jira Plugin handling subscriptions fails to check the security level of an incoming issue or limit it based on the user who created the subscription resulting in registered users on Jira being able to create webhooks that give them access to all Jira issues.
CVSS Score
3.4
EPSS Score
0.005
Published
2024-02-09
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