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CVE-2017-18897

20
FAUCET Score

CVE-2017-18897 describes a vulnerability in Mattermost Server versions prior to 4.2.0, 4.1.1, and 4.0.5 when configured as an OAuth 2.0 service provider. This medium-severity vulnerability (CVSS 6.1) is due to improper handling of a "deny" action during redirection, potentially leading to information disclosure or manipulation (CWE-601). While it requires user interaction and network access, there is no evidence of active exploitation, public exploit code, or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 4.0.5CPE matchmatch criteria
cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
>= 4.1.0, < 4.1.1CPE matchmatch criteria
cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
4.2.0CPE matchmatch criteria
cpe:2.3:a:mattermost:mattermost_server:4.2.0:rc1:*:*:*:*:*:*
4.2.0CPE matchmatch criteria
cpe:2.3:a:mattermost:mattermost_server:4.2.0:rc2:*:*:*:*:*:*
4.2.0CPE matchmatch criteria
cpe:2.3:a:mattermost:mattermost_server:4.2.0:rc3:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

6.1MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality Impact
LOW
Integrity Impact
LOW
Availability Impact
NONE
Exploitability Score
2.8
Impact Score
2.7
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.69%
Probability of exploitation in next 30 days
EPSS Percentile
48.9%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0069 is in the 54th percentile among its peer group of 26,234 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (3)

gopatch availablevia ghsa
Product: github.com/mattermost/mattermost-serverFixed in: 4.0.5
gopatch availablevia ghsa
Product: github.com/mattermost/mattermost-serverFixed in: 4.1.1
gopatch availablevia ghsa
Product: github.com/mattermost/mattermost-serverFixed in: 4.2.0

Vendor Advisories (1)

goGHSA-f7c3-7vp3-44p6medium

Mattermost Server mishandles redirect denial action

May 24, 2022

References

mattermost.com / security-updates
Vendor Advisory