Security Digest · Vulnerability record
CVE-2024-39274: Mattermost failed to properly validate that the channel that comes from the sync message is a shared channel
Mattermost versions 9.9.x
CVSS 9.3 Critical EPSS 0.3% · p26
Should you act?
Critical, preconditions apply
Severe if exploited, but exploitation needs conditions that may not apply to you. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.
- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 0.3%, percentile 26: FIRST’s model estimates a 0.3% chance of exploitation activity in the next 30 days, higher than 26% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Needs an account (high (admin)). Exposure depends on who can log in.
- Only applies if your dependency tree includes
github.com/mattermost/mattermost/server/v8(Go) >= 9.5.0, < 9.5.7, fixed in 9.5.7;github.com/mattermost/mattermost/server/v8(Go) >= 9.7.0, < 9.7.6, fixed in 9.7.6;github.com/mattermost/mattermost/server/v8(Go) >= 9.8.0, < 9.8.2, fixed in 9.8.2;github.com/mattermost/mattermost/server/v8(Go) = 9.9.0, fixed in 9.9.1. Check your lockfile, including transitive dependencies.
What it is
Mattermost versions 9.9.x
From the GitHub advisory
Mattermost versions 9.9.x
Weakness type: CWE-284.
Product: github.com/mattermost/mattermost/server/v8 (Go) · Assigned by: Mattermost · Published: 2024-08-01
Affected and fixed versions
| Ecosystem | Package | Vulnerable | First fixed |
|---|---|---|---|
| Go | github.com/mattermost/mattermost/server/v8 | >= 9.5.0, < 9.5.7 | 9.5.7 |
| Go | github.com/mattermost/mattermost/server/v8 | >= 9.7.0, < 9.7.6 | 9.7.6 |
| Go | github.com/mattermost/mattermost/server/v8 | >= 9.8.0, < 9.8.2 | 9.8.2 |
| Go | github.com/mattermost/mattermost/server/v8 | = 9.9.0 | 9.9.1 |
| Vendor | Product | Affected versions (per CVE record) |
|---|---|---|
| Mattermost | Mattermost | 9.9.0, 9.5.0 <= 9.5.6, 9.7.0 <= 9.7.5, 9.8.0 <= 9.8.1 |
Severity scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| Mattermost | 3.1 | 8.7 High | CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N |
| GitHub | 4.0 | 9.3 | CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N |
- Attack vector: network (remotely reachable)
- Attack complexity: low
- Attack requirements: none
- Privileges required: high (admin)
- User interaction: none
CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.
Exploitation and urgency
- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none, automatable no, technical impact total.
- FIRST EPSS (model of 2026-10-21): 0.34% probability of exploitation activity in the next 30 days; percentile 26.
Timeline
- — CVE record published by Mattermost
- — GitHub-reviewed advisory GHSA-cmc8-222c-vqp9 published (critical)
- — CVE record last updated
Sources and references
Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.
Vulnerability records
- GitHub Advisory GHSA-cmc8-222c-vqp9 github.com
- CVE.org record CVE-2024-39274 cve.org
- NVD entry CVE-2024-39274 nvd.nist.gov
Other references from the CVE record and advisory
- mattermost.com mattermost.com
- pkg.go.dev pkg.go.dev