How severe is GHSA-679f-wmrg-qf57?

GHSA-679f-wmrg-qf57 has a CVSS score of 4.3/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by GHSA-679f-wmrg-qf57?

GHSA-679f-wmrg-qf57 affects the following packages: github.com/mattermost/mattermost/server/v8 (Go), github.com/mattermost/mattermost-server (Go), github.com/mattermost/mattermost-server (Go), github.com/mattermost/mattermost-server (Go), github.com/mattermost/mattermost-server (Go). Ecosystems affected: Go.

How do I fix GHSA-679f-wmrg-qf57?

Update github.com/mattermost/mattermost/server/v8 to 8.0.0-20260113182106-a18b80ba4c32 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-679f-wmrg-qf57 is resolved across your whole dependency graph.

How do I detect GHSA-679f-wmrg-qf57 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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate GHSA-679f-wmrg-qf57 if there is no patch (or I can't update yet)?

Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Is GHSA-679f-wmrg-qf57 actively exploited in the wild?

No public exploit code has been indexed for GHSA-679f-wmrg-qf57 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 is the EPSS score for GHSA-679f-wmrg-qf57?

GHSA-679f-wmrg-qf57 has an EPSS (Exploit Prediction Scoring System) score of 0.2%, placing it in the 7th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is GHSA-679f-wmrg-qf57?

GHSA-679f-wmrg-qf57 is classified as CWE-862 (CWE-862). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was GHSA-679f-wmrg-qf57 published, and has it been updated?

GHSA-679f-wmrg-qf57 was published on March 16, 2026 and was last updated on March 23, 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

MEDIUM severity

Mattermost allows a removed team member to enumerate all public channels within a private teamGHSA-679f-wmrg-qf57

MEDIUMFix: mattermost/mattermost@a18b80b

GHSA-679f-wmrg-qf57 is a medium-severity (CVSS 4.3) CWE-862 vulnerability in github.com/mattermost/mattermost/server/v8. A fix is available for github.com/mattermost/mattermost/server/v8 — see the affected versions and patch details below.

Also known asCVE-2026-2458GO-2026-4729

Published

Mar 16, 2026

Updated

Mar 23, 2026

Affected

5 pkgs

Patched

5 / 5

Exploits

None indexed

Exploitation data as of Nov 9, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for GHSA-679f-wmrg-qf57.

EPSS Exploitation Probability

via FIRST.org ↗

0.2%probability of exploitation in next 30 days

Lower Risk+0.00%

Lower risk than most CVEs7th percentile — riskier than 7% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

5 pkgs affected

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

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 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to properly validate team membership when searching channels which allows a removed team member to enumerate all public channels within a private team via the channel search API endpoint.. Mattermost Advisory ID: MMSA-2025-00568

Affected Packages

5 total 5 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/mattermost/mattermost/server/v8`	all versions	8.0.0-20260113182106-a18b80ba4c32`go get github.com/mattermost/mattermost/server/v8@v8.0.0-20260113182106-a18b80ba4c32`
🐹Go	`github.com/mattermost/mattermost-server`	all versions	5.3.2-0.20260113182106-a18b80ba4c32`go get github.com/mattermost/mattermost-server@v5.3.2-0.20260113182106-a18b80ba4c32`
🐹Go	`github.com/mattermost/mattermost-server`	≥ 10.11.0-rc1&&< 10.11.11	10.11.11`go get github.com/mattermost/mattermost-server@v10.11.11`
🐹Go	`github.com/mattermost/mattermost-server`	≥ 11.2.0-rc1&&< 11.2.3	11.2.3`go get github.com/mattermost/mattermost-server@v11.2.3`
🐹Go	`github.com/mattermost/mattermost-server`	≥ 11.3.0-rc1&&< 11.3.1	11.3.1`go get github.com/mattermost/mattermost-server@v11.3.1`

Affected Products

1 product · 3 configurations

Application

mattermost servermattermost

≥ 11.3.0 && < 11.3.1

range

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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/mattermost/mattermost/server/v8 to 8.0.0-20260113182106-a18b80ba4c32 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-679f-wmrg-qf57 is resolved across your whole dependency graph.
Workarounds
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Frequently Asked Questions

O3 Security · Impact-Aware SCA

Is GHSA-679f-wmrg-qf57 in your dependencies?

Find it across Go, including transitive dependencies.

Scan my dependencies How O3 SCA works

CVSS Score

4.3/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

None

Availability

None

Raw vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

CWE Classification

CWE-862CWE-862

Weaponization

No Nuclei template, Metasploit module or public proof-of-concept found.

Timeline

Disclosed

Mar 16, 2026

Last updated

Mar 23, 2026

Identifiers

GHSA-679f-wmrg-qf57

GO-2026-4729

References

Advisorynvd.nist.gov · CVE 2026 2458 Webgithub.com · a18b80ba4c324b74b3d47951c33957305af4a099 Webmattermost.com · security updates Packagegithub.com · mattermost

Related vulnerabilities

This CVE is medium severity; 7 of 8 other CVEs affecting v8 are rated as high or higher (top: high).

CVE-2026-8823CVE-2026-6046CVE-2026-7387CVE-2026-6961CVE-2026-7184CVE-2026-6689CVE-2026-6739CVE-2026-3433

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedMar 23, 2026

Mattermost allows a removed team member to enumerate all public channels within a private teamGHSA-679f-wmrg-qf57

Exploitation Status

No confirmed exploitation observed yet

EPSS Exploitation Probability

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

Description

Affected Packages

Affected Products

Detection & mitigation playbook

Detect

Fix

Workarounds

Frequently Asked Questions

Is GHSA-679f-wmrg-qf57 in your dependencies?