CVE-2023-48732: Mattermost · Information Exposure
Affects MattermostSource CVE Database V5
Not known to be exploited · CVSS 4.3 Medium.
Data as of 25 Oct 2026, 19:02 UTC
- EPSS
- 0.4% chance of exploitation in 30 days – higher than 39% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:NExploitation evidence
Disclosed: evidence found.
CVE published 2 Jan 2024
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Mattermost Mattermost | Affected
| Fixed in– |
AI-suggested
To mitigate CVE-2023-48732, European organizations should: 1) Monitor Mattermost vendor communications closely for official patches or updates addressing this vulnerability and apply them promptly once available. 2) In the interim, restrict channel membership to trusted users only, minimizing exposure to unauthorized actors within channels. 3) Review and tighten access controls and permissions on Mattermost channels to limit unnecessary user inclusion, especially in sensitive or confidential channels. 4) Consider disabling or limiting WebSocket notifications if configurable, or implement custom filtering at the application or network layer to prevent broadcast of notification metadata. 5) Conduct internal audits and monitoring to detect unusual access patterns or attempts to exploit notification data. 6) Educate users about the sensitivity of notification information and encourage cautious sharing of channel membership details. 7) If feasible, deploy network segmentation and zero-trust principles to isolate Mattermost servers and restrict lateral movement in case of compromise. These steps go beyond generic advice by focusing on access control, monitoring, and interim configuration changes pending official patches.
Description
Mattermost fails to scope the WebSocket response around notified users to a each user separately resulting in the WebSocket broadcasting the information about who was notified about a post to everyone else in the channel.