CVE-2024-39777
Malicious remote can invite itself to an arbitrary local channel
Mattermost versions 9.9.x <= 9.9.0, 9.5.x <= 9.5.6, 9.7.x <= 9.7.5 and 9.8.x <= 9.8.1 fail to disallow unsolicited invites to expose access to local channels, when shared channels are enabled, which allows a malicious remote to send an invite with the ID of an existing local channel, and that local channel will then become shared without the consent of the local admin.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- High
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
Malicious remote can invite itself to an arbitrary local channel
Mattermost versions 9.9.x <= 9.9.0, 9.5.x <= 9.5.6, 9.7.x <= 9.7.5 and 9.8.x <= 9.8.1 fail to disallow unsolicited invites to expose access to local channels, when shared channels are enabled, which allows a malicious remote to send an invite with the ID of an existing local channel, and that local channel will then become shared without the consent of the local admin.
- Record
CVE-2024-39777- CVSS 3.1
- 8.7 High
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N - Weakness
- CWE-284
- Updated
- 2026-11-02
EUVDEUVD-2024-2628
Mattermost versions 9.9.x <= 9.9.0, 9.5.x <= 9.5.6, 9.7.x <= 9.7.5 and 9.8.x <= 9.8.1 fail to disallow unsolicited invites to expose access to local channels, when shared channels are enabled, which allows a malicious remote to send an invite with the ID of an existing local channel, and that local channel will then become shared without the consent of the local admin.
- Record
EUVD-2024-2628- CVSS 3.1
- 8.7 High
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N - Updated
- 2026-11-03
GitHub AdvisoriesGHSA-q22q-2rrf-m27p
Mattermost allows unsolicited invites to expose access to local channels
Mattermost versions 9.9.x <= 9.9.0, 9.5.x <= 9.5.6, 9.7.x <= 9.7.5 and 9.8.x <= 9.8.1 fail to disallow unsolicited invites to expose access to local channels, when shared channels are enabled, which allows a malicious remote to send an invite with the ID of an existing local channel, and that local channel will then become shared without the consent of the local admin.
- Record
GHSA-q22q-2rrf-m27p- CVSS 4.0
- 9.3 Critical
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 - CVSS 3.1
- 8.7 High
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N - Weakness
- CWE-284
- Updated
- 2026-11-02
NVD
Mattermost versions 9.9.x <= 9.9.0, 9.5.x <= 9.5.6, 9.7.x <= 9.7.5 and 9.8.x <= 9.8.1 fail to disallow unsolicited invites to expose access to local channels, when shared channels are enabled, which allows a malicious remote to send an invite with the ID of an existing local channel, and that local channel will then become shared without the consent of the local admin.
- Record
CVE-2024-39777- CVSS 3.1
- 8.7 High
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N - CVSS 3.1
- 9.6 Critical
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N - Weakness
- CWE-284
- Updated
- 2026-11-02
OSV
Malicious remote can invite itself to an arbitrary local channel
Mattermost versions 9.9.x <= 9.9.0, 9.5.x <= 9.5.6, 9.7.x <= 9.7.5 and 9.8.x <= 9.8.1 fail to disallow unsolicited invites to expose access to local channels, when shared channels are enabled, which allows a malicious remote to send an invite with the ID of an existing local channel, and that local channel will then become shared without the consent of the local admin.
- Record
CVE-2024-39777- CVSS 3.1
- 8.7 High
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N - Weakness
- CWE-284
- Updated
- 2026-11-02
OSVGHSA-q22q-2rrf-m27p
Mattermost allows unsolicited invites to expose access to local channels
Mattermost versions 9.9.x <= 9.9.0, 9.5.x <= 9.5.6, 9.7.x <= 9.7.5 and 9.8.x <= 9.8.1 fail to disallow unsolicited invites to expose access to local channels, when shared channels are enabled, which allows a malicious remote to send an invite with the ID of an existing local channel, and that local channel will then become shared without the consent of the local admin.
- Record
GHSA-q22q-2rrf-m27p- CVSS 4.0
- 9.3 Critical
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 - CVSS 3.1
- 8.7 High
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N - Weakness
- CWE-284
- Updated
- 2026-11-02
OSVGO-2024-3092 No score
Mattermost allows unsolicited invites to expose access to local channels in github.com/mattermost/mattermost-server
Mattermost allows unsolicited invites to expose access to local channels in github.com/mattermost/mattermost-server
- Record
GO-2024-3092- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
github.com/mattermost/mattermost/server/v8Go |
9.9.0 up to 9.9.1 | 9.9.1 |
github.com/mattermost/mattermost/server/v8Go |
9.5.0 up to 9.5.7 | 9.5.7 |
github.com/mattermost/mattermost/server/v8Go |
9.7.0 up to 9.7.6 | 9.7.6 |
github.com/mattermost/mattermost/server/v8Go |
9.8.0 up to 9.8.1 | 9.8.1 |
github.com/mattermost/mattermost-serverGo |
9.5.0+incompatible up to 9.5.7+incompatible, 9.7.0+incompatible up to 9.7.6+incompatible, 9.8.0+incompatible up to 9.8.1+incompatible, 9.9.0+incompatible up to 9.9.1+incompatible | 9.5.7+incompatible9.7.6+incompatible9.8.1+incompatible9.9.1+incompatible |
github.com/mattermost/mattermost-server/v5Go |
All versions | None known |
github.com/mattermost/mattermost-server/v6Go |
All versions | None known |
github.com/mattermost/mattermost/server/v8Go |
All versions | None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases, published | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2024-39777 is a high vulnerability (CVSS 8.7) in Mattermost, published August 1, 2024. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.36%, the 30th percentile. Fixed in github.com/mattermost/mattermost/server/v8 9.9.1.