How severe is CVE-2024-39777?

CVE-2024-39777 has a CVSS score of 8.7/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2024-39777?

CVE-2024-39777 affects the following packages: github.com/mattermost/mattermost/server/v8 (Go), github.com/mattermost/mattermost/server/v8 (Go), github.com/mattermost/mattermost/server/v8 (Go), github.com/mattermost/mattermost/server/v8 (Go). Ecosystems affected: Go.

How do I fix CVE-2024-39777?

Update github.com/mattermost/mattermost/server/v8 to 9.9.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-39777 is resolved across your whole dependency graph.

How do I detect CVE-2024-39777 in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/mattermost/mattermost/server/v8. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate CVE-2024-39777 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against CVE-2024-39777?

O3 pinpoints whether CVE-2024-39777 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is CVE-2024-39777 actively exploited in the wild?

No public exploit code has been indexed for CVE-2024-39777 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What type of vulnerability is CVE-2024-39777?

CVE-2024-39777 is classified as CWE-284 (CWE-284). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2024-39777 published, and has it been updated?

CVE-2024-39777 was published on August 1, 2024 and was last updated on July 15, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐹

🐹 Go

Not in CISA KEV

HIGH severity

CVE-2024-39777

HIGH

CVE-2024-39777 is a high-severity (CVSS 8.7) CWE-284 vulnerability in github.com/mattermost/mattermost/server/v8. O3 Security confirms whether CVE-2024-39777 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

Malicious remote can invite itself to an arbitrary local channel

Also known asGHSA-q22q-2rrf-m27pGO-2024-3092

Published

Aug 1, 2024

Updated

Jul 15, 2026

Affected

4 pkgs

Patched

4 / 4

Exploits

None indexed

Exploitation data as of Jul 15, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Real-World Exposure

4 pkgs affected

🐹github.com/mattermost/mattermost/server/v8🐹github.com/mattermost/mattermost/server/v8🐹github.com/mattermost/mattermost/server/v8🐹github.com/mattermost/mattermost/server/v8

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

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.

Affected Packages

4 total 4 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/mattermost/mattermost/server/v8`	≥ 9.9.0&&< 9.9.1	9.9.1
🐹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&&< 9.8.1	9.8.1

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/mattermost/mattermost/server/v8. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update github.com/mattermost/mattermost/server/v8 to 9.9.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-39777 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2024-39777 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to CVE-2024-39777. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

O3 Security · Impact-Aware SCA

Is CVE-2024-39777 in your dependencies?

O3 detects CVE-2024-39777 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my dependencies How O3 SCA works