CVE-2017-18894

mediumpriority · track · 32EPSS 0.008 · 57 %ileEUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

0.83% (57th) EPSS

CVSS 5.5 · medium

Is it mine?

10 products

Check your exposure

Who says so?

4 sources

cnnvd · enisa_euvd · osv · nvd

EPSS · scored 2026-10-28

An issue was discovered in Mattermost Server before 4.2.0, 4.1.1, and 4.0.5, when used as an OAuth 2.0 service provider. Sometimes. resource-owner authorization is bypassed, allowing account takeover.

cvss

Technical severity, 0–10. One row per scoring source.

8.1

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 5.5–8.1

v2.05.5mediumAV:N/AC:L/Au:S/C:P/I:P/A:Nprimary · NVD / NIST USexploitability 8 · impact 4.9

v3.18.1highCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Nprimary · NVD / NIST USexploitability 2.8 · impact 5.2

v3.18.1highCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Nsecondary · OSV

v3.17.4highCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N/E:Usecondary · CVSS-BT (t0sche)

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-732USprimaryCWE-639USCWE-732US

affected products (10)

Products and version ranges known to be affected.

n/a n/a≤ n/aenisa_euvdEU
mattermost mattermost server< 4.0.5nvdUScpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
mattermost mattermost server4.1.0 → 4.1.1nvdUScpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
mattermost mattermost server= 4.2.0nvdUScpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
Go github.com/mattermost/mattermost-server< 4.0.5osvUSpkg:golang/github.com/mattermost/mattermost-server
Go github.com/mattermost/mattermost-server< 4.0.5+incompatibleosvUSpkg:golang/github.com/mattermost/mattermost-server
Go github.com/mattermost/mattermost-server4.1.0 → 4.1.1osvUSpkg:golang/github.com/mattermost/mattermost-server
Go github.com/mattermost/mattermost-server4.1.0+incompatible → 4.1.1+incompatibleosvUSpkg:golang/github.com/mattermost/mattermost-server
Go github.com/mattermost/mattermost-server4.2.0-rc1 → 4.2.0osvUSpkg:golang/github.com/mattermost/mattermost-server
Go github.com/mattermost/mattermost-server4.2.0-rc1+incompatible → 4.2.0+incompatibleosvUSpkg:golang/github.com/mattermost/mattermost-server

advisories (2)

Vendor and ecosystem advisories describing this.

GHSA-gg42-mwr6-p82cMattermost Server has intermittent Authorization bypass for resource-owners2022-05-24ghsa · osvUS
An issue was discovered in Mattermost Server before 4.2.0, 4.1.1, and 4.0.5, when used as an OAuth 2.0 service provider. Resource-owner authorization can be intermittently bypassed, allowing account takeover.
GO-2026-4297Mattermost Server has intermittent Authorization bypass for resource-owners in github.com/mattermost/mattermost-server2026-01-13vendor · osvUS
Mattermost Server has intermittent Authorization bypass for resource-owners in github.com/mattermost/mattermost-server

also known as (5)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd osv nvd NVD CVE.org MITRE

published 2020-06-19modified 2026-06-17

related (1,935)

Related entries.

ID	severity	EPSS	exploitable	published
CVE-2022-22960US	high7.8OT critical	35.5% (98th)	KEV	2022-04-13
VMware Workspace ONE Access, Identity Manager and vRealize Automation contain a privilege escalation vulnerability due to improper permissions in support scripts. A malicious actor…
CVE-2021-23874US	high7.8OT critical	1.03% (63rd)	KEV	2021-02-10
Arbitrary Process Execution vulnerability in McAfee Total Protection (MTP) prior to 16.0.30 allows a local user to gain elevated privileges and execute arbitrary code bypassing MTP…
CVE-2019-15752US	high7.8OT critical	48.6% (99th)	KEV	2019-08-28
Docker Desktop Community Edition before 2.1.0.1 allows local users to gain privileges by placing a Trojan horse docker-credential-wincred.exe file in %PROGRAMDATA%\DockerDesktop\ve…
CVE-2018-13374US	medium4.3OT critical	38.1% (99th)	KEV	2019-01-22
A Improper Access Control in Fortinet FortiOS 6.0.2, 5.6.7 and before, FortiADC 6.1.0, 6.0.0 to 6.0.1, 5.4.0 to 5.4.4 allows attacker to obtain the LDAP server login credentials co…
CVE-2021-25646US	high8.8	99.1% (100th)	Exploit	2021-01-29
Apache Druid includes the ability to execute user-provided JavaScript code embedded in various types of requests. This functionality is intended for use in high-trust environments,…

+1930 more

references (4)

External citations — patches, advisories, analysis.

scry

Attackers weaponise vulnerabilities like this against internet-exposed services. See what is exposed on your perimeter with a free passive scan.

Free scan