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CVE-2026-9820

Mattermost schemes teams endpoint exposes private team invite IDs

LOW

3.8

CVSS Score

Published: July 13, 2026 at 10:51 AM UTC

Updated: July 13, 2026 at 08:57 PM UTC

2 products affected across 1 vendorMattermost ServerMattermost

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Severity

LOW3.8

Exploit prediction

EPSS 0.3%

SSVC

No known exploit

Description

Mattermost versions 11.7.x <= 11.7.2, 10.11.x <= 10.11.19 fail to sanitize team objects returned by the scheme teams endpoint, which allows a user with the User Manager role to obtain invite links for private teams and use them to join or share access to those teams via the scheme teams API endpoint.. Mattermost Advisory ID: MMSA-2026-00671

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Mattermost Server · Mattermost

95%

10.11.0 ≤ v < 10.11.2011.7.0 ≤ v < 11.7.3

Affected range stops below 10.11.20, so it looks safe — our inference, not a vendor statement

Affected range stops below 11.7.3, so it looks safe — our inference, not a vendor statement

Mattermost · Mattermost

60%

10.11.0 ≤ v ≤ 10.11.1911.7.0 ≤ v ≤ 11.7.210.11.0 11.7.0

Vendor states this is fixed in 10.11.20 (unaffected)

Vendor states this is fixed in 11.7.3 (unaffected)

Vendor states this is fixed in 11.8.0 (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

https://mattermost.com/security-updates

References (1)

Vendor Advisory

Source: cverecord

https://mattermost.com/security-updates

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

3.8LOWMattermost

Attack Vector: NETWORK
Complexity: LOW
Privileges: HIGH
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: LOW
Integrity: LOW
Availability: NONE

Vector?

Quick Info

StatusANALYZED

CWE

CWE-862

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