Overview
CVE-2025-55073 is a medium-severity vulnerability affecting Mattermost, a popular open-source collaboration platform. This flaw allows a remote attacker to edit arbitrary posts within the Mattermost environment by exploiting a weakness in the validation of the relationship between post updates and the MSTeams plugin OAuth flow.
Technical Details
The vulnerability lies in the improper validation of the association between a post being updated and the MSTeams plugin OAuth flow. Specifically, versions 10.11.x (<= 10.11.3), 10.5.x (<= 10.5.11), and 10.12.x (<= 10.12.0) of Mattermost fail to adequately verify the legitimacy of the OAuth redirect URL used by the MSTeams plugin. By crafting a malicious MSTeams plugin OAuth redirect URL, an attacker can bypass security checks and gain the ability to modify the content of any post, regardless of their permissions or ownership.
CVSS Analysis
The Common Vulnerability Scoring System (CVSS) assigns CVE-2025-55073 a score of 5.4, indicating a MEDIUM severity. The CVSS vector string would typically include metrics for attack vector, attack complexity, privileges required, user interaction, scope, confidentiality impact, integrity impact, and availability impact. While the exact vector may vary slightly depending on the assessment, the score reflects the relatively low complexity of the attack and the potential for significant impact on data integrity.
Possible Impact
The successful exploitation of CVE-2025-55073 can have serious consequences:
- Data Manipulation: Attackers can alter important information within Mattermost channels, potentially spreading misinformation or damaging trust within teams.
- Reputation Damage: Modified posts could be used to deface internal communications, leading to reputational damage for the organization using Mattermost.
- Business Disruption: Changes to critical information can disrupt workflows and impact productivity.
- Social Engineering: Maliciously edited posts could be used to trick users into revealing sensitive information.
Mitigation or Patch Steps
To address CVE-2025-55073, it is crucial to upgrade your Mattermost instance to a patched version. Specifically, upgrade to a version later than:
- 10.11.3 if you are on the 10.11.x branch
- 10.5.11 if you are on the 10.5.x branch
- 10.12.0 if you are on the 10.12.x branch
Refer to the official Mattermost security update and release notes for detailed instructions on upgrading your Mattermost server. It is always recommended to test upgrades in a non-production environment before applying them to production systems.
