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CVE-2017-18873

20
FAUCET Score

CVE-2017-18873 describes a denial-of-service vulnerability in Mattermost Server versions prior to 4.3.0, 4.2.1, and 4.1.2. An unauthenticated attacker can exploit this flaw by sending a specially crafted, misformatted post, leading to channels becoming invisible to users. This issue is rated Medium severity (CVSS 5.3) due to its low attack complexity and potential for denial of service, though it does not impact confidentiality or integrity. There is no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or inclusion in CISA's KEV catalog, with minimal community discussion and media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
< 4.1.2CPE matchmatch criteria
cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
>= 4.2.0, < 4.2.1CPE matchmatch criteria
cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
4.3.0CPE matchmatch criteria
cpe:2.3:a:mattermost:mattermost_server:4.3.0:rc1:*:*:*:*:*:*
4.3.0CPE matchmatch criteria
cpe:2.3:a:mattermost:mattermost_server:4.3.0:rc2:*:*:*:*:*:*
4.3.0CPE matchmatch criteria
cpe:2.3:a:mattermost:mattermost_server:4.3.0:rc3:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

5.3MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
LOW
Exploitability Score
3.9
Impact Score
1.4
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.11%
Probability of exploitation in next 30 days
EPSS Percentile
62.4%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0111 is in the 40th percentile among its peer group of 23,723 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.4 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.0 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: 4.1.2-0.20171013141717-ee57a5829ab1
gopatch availablevia ghsa
Product: github.com/mattermost/mattermost-serverFixed in: 4.2.1-0.20171013140502-b3e4b0ac9168
gopatch availablevia ghsa
Product: github.com/mattermost/mattermost-serverFixed in: 4.3.0

Vendor Advisories (1)

goGHSA-x6mw-hf2j-vqpcmedium

Mattermost Server is vulnerable to channel invisibility DoS via misformatted post

May 24, 2022

References

mattermost.com / security-updates
Vendor Advisory