CVE-2018-21251 describes a critical authorization bypass vulnerability in Mattermost Server versions prior to 5.2 and 5.1.1, where differing channel names in request parameters and body could allow unauthorized access. With a CVSS score of 9.8, this network-exploitable flaw requires no user interaction and can lead to complete compromise of confidentiality, integrity, and availability. Despite its severity, there is no evidence of active exploitation, public exploit code, or significant community discussion, and it is not listed in CISA's KEV catalog.
| Vendor | Product | Version(s) | CPE |
|---|---|---|---|
< 5.1.1CPE matchmatch criteria | cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:* | ||
5.2.0CPE matchmatch criteria | cpe:2.3:a:mattermost:mattermost_server:5.2.0:rc1:*:*:*:*:*:* | ||
5.2.0CPE matchmatch criteria | cpe:2.3:a:mattermost:mattermost_server:5.2.0:rc2:*:*:*:*:*:* | ||
5.2.0CPE matchmatch criteria | cpe:2.3:a:mattermost:mattermost_server:5.2.0:rc3:*:*:*:*:*:* | ||
5.2.0CPE matchmatch criteria | cpe:2.3:a:mattermost:mattermost_server:5.2.0:rc4:*:*:*:*:*:* |
CVSS version used by this source: 3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.
No media coverage found for this CVE.
The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.
Remediation records are not available for this CVE.