GHSA-h998-hxxj-8q83 CVE-2026-9162 GO-2026-6482
Mattermost doesn't invalidate cached authentication state for active WebSocket connections during global session revocation
- Severity
- 4.3 / 10
- Medium · CVSS 3.1
- Exploit chance (EPSS)
- 0.33%
- Chance of exploitation in the next 30 days. Higher than 26.85% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-613 Insufficient Session Expiration
- Fix
11.7.1- Upgrade github.com/mattermost/mattermost-server to this version or later
Description
Mattermost versions 11.7.x <= 11.7.0, 11.6.x <= 11.6.2, 11.5.x <= 11.5.5, 10.11.x <= 10.11.17 fail to invalidate cached authentication state for active WebSocket connections during global session revocation, which allows a user with an existing WebSocket connection to remain authenticated and continue receiving real-time events until the cached session expires or the client reconnects.. Mattermost Advisory ID: MMSA-2026-00664
Affected versions
Go
| Package | Vulnerable | Fixed in |
|---|---|---|
| github.com/mattermost/mattermost-server | >= 11.7.0, < 11.7.1 |
11.7.1 |
| github.com/mattermost/mattermost-server | >= 11.6.0, < 11.6.3 |
11.6.3 |
| github.com/mattermost/mattermost-server | >= 11.5.0, < 11.5.6 |
11.5.6 |
| github.com/mattermost/mattermost-server | >= 10.11.0, < 10.11.18 |
10.11.18 |
| github.com/mattermost/mattermost-server | >= 10.11.0+incompatible, < 10.11.18+incompatible>= 11.5.0+incompatible, < 11.5.6+incompatible>= 11.6.0+incompatible, < 11.6.3+incompatible>= 11.7.0+incompatible, < 11.7.1+incompatible |
10.11.18+incompatible11.5.6+incompatible11.6.3+incompatible11.7.1+incompatible |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
github.com/mattermost/mattermost-server Go → 11.7.1
- go
go get github.com/mattermost/mattermost-server@v11.7.1 && go mod tidy
Severity breakdown
CVSS 3.1 4.3
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- Low
- Integrity
- None
- Availability
- None
Weakness
CWE-613: Insufficient Session Expiration
According to WASC, "Insufficient Session Expiration is when a web site permits an attacker to reuse old session credentials or session IDs for authorization."
How to prevent it
- Implementation: Set sessions/credentials expiration date.
References
Advisories
Packages
Other links
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-xmfh-3ccg-c9fx Mattermost has an Incorrect Authorization issue | Low | Also affects github.com/mattermost/mattermost-server |
| GHSA-g5vr-6pgg-74qv Mattermost doesn't enforce bot-specific permission checks on the user active status endpoint | Low | Also affects github.com/mattermost/mattermost-server |
| GHSA-jqgv-39mg-7c2r Mattermost doesn't authenticate Atlassian Connect installed callbacks, allowing a remote unauthenticated attacker to inject a rogue sharedSecret | Medium | Also affects github.com/mattermost/mattermost-server |
| GHSA-mxq2-5jpg-7474 Mattermost doesn't validate channel ownership of an existing subscription before applying edits | Medium | Also affects github.com/mattermost/mattermost-server |
| GHSA-2g8v-grq3-hq2g Mattermost doesn't enforce administrator authorization on the {{setDefaultInstance}} call within the {{/gitlab connect}} command handler | Medium | Also affects github.com/mattermost/mattermost-server |
| GHSA-6hxm-w4hv-vgvw Mattermost doesn't require role-management authorization when setting the scheme_admin flag on group syncable link and patch endpoints | High | Also affects github.com/mattermost/mattermost-server |
| GHSA-9p44-r552-4wp9 Mattermost doesn't sanitize the Remote Cluster API response on PATCH operations | Medium | Also affects github.com/mattermost/mattermost-server |
| GHSA-8qq9-cqj8-82w4 Mattermost doesn't sanitize FileInfo.Name received from federated peers during shared channel file sync | High | Also affects github.com/mattermost/mattermost-server |
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