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CVE-2017-18907

20
FAUCET Score

CVE-2017-18907 describes a Cross-Site Scripting (XSS) vulnerability in Mattermost Server versions prior to 4.0.0, 3.10.2, and 3.9.2, specifically exploitable through a channel header. This medium-severity flaw (CVSS 6.1) requires user interaction (UI:R) and could lead to limited confidentiality and integrity impacts (C:L/I:L) if exploited. There is no evidence of active exploitation, nor are there publicly available exploit modules in Metasploit, Nuclei, or ExploitDB, despite some community discussion and media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
< 3.9.2CPE matchmatch criteria
cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
>= 3.10.0, < 3.10.2CPE matchmatch criteria
cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*

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
49.0%
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 26,221 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

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 (2)

gopatch availablevia ghsa
Product: github.com/mattermost/mattermost-serverFixed in: 3.9.2-0.20170714014920-312269ad0bd1
gopatch availablevia ghsa
Product: github.com/mattermost/mattermost-serverFixed in: 3.10.2

Vendor Advisories (1)

goGHSA-42x9-rr3c-gr59medium

Mattermost Server vulnerable to XSS through channel headers

May 24, 2022

References

mattermost.com / security-updates
Vendor Advisory