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Mattermost vulnerable to denial of service via large number of emoji reactions

Moderate severity GitHub Reviewed Published Feb 9, 2024 to the GitHub Advisory Database • Updated Feb 19, 2025

Package

gomod github.com/mattermost/mattermost/server/v8 (Go)

Affected versions

< 8.1.8
>= 9.2.0, < 9.2.4
>= 9.1.0, < 9.1.5

Patched versions

8.1.8
9.2.4
9.1.5

Description

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. Fetching posts with huge amounts of reactions results in Uncontrolled Resource Consumption.

References

Published by the National Vulnerability Database Feb 9, 2024
Published to the GitHub Advisory Database Feb 9, 2024
Reviewed Feb 9, 2024
Last updated Feb 19, 2025

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(33rd percentile)

Weaknesses

CVE ID

CVE-2024-1402

GHSA ID

GHSA-32h7-7j94-8fc2

Source code

Credits

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