CVE-2017-18897

mediumpriority · track · 24EPSS 0.007 · 53 %ileEUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

0.69% (53rd) EPSS

CVSS 5.8 · 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. It mishandles a deny action for a redirection.

cvss

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

6.1

010

base score 0–10 · higher = more severe · hover a vector to decode

v2.05.8mediumAV:N/AC:M/Au:N/C:P/I:P/A:Nprimary · NVD / NIST USexploitability 8.6 · impact 4.9

v3.16.1mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:Nprimary · NVD / NIST USexploitability 2.8 · impact 2.7

v3.16.1mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:Nsecondary · OSV

v3.15.6mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N/E:Usecondary · CVSS-BT (t0sche)

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-601USprimaryCWE-601US

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-f7c3-7vp3-44p6Mattermost Server mishandles redirect denial action2022-05-24ghsa · 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. It mishandles a deny action for a redirection.
GO-2026-4301Mattermost Server mishandles redirect denial action in github.com/mattermost/mattermost-server2026-01-13vendor · osvUS
Mattermost Server mishandles redirect denial action 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

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references (4)

External citations — patches, advisories, analysis.

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