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CVE-2017-18878

17
FAUCET Score

CVE-2017-18878 is a medium-severity vulnerability affecting Mattermost Server versions prior to 4.3.0, 4.2.1, and 4.1.2. It allows an authenticated attacker, with knowledge of a session ID, to revoke another user's session, leading to a denial of service for that user. The vulnerability has a low attack complexity and does not appear to be actively exploited, with no public exploit code or significant community discussion.

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

4.3MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
LOW
Exploitability Score
2.8
Impact Score
1.4
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.77%
Probability of exploitation in next 30 days
EPSS Percentile
51.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-24
Model: v2026.06.15
This CVE's current EPSS score of 0.0077 is in the 63rd percentile among its peer group of 21,924 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 0.0 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: 4.1.2-0.20171004201910-6be8113eb60c
gopatch availablevia ghsa
Product: github.com/mattermost/mattermost-serverFixed in: 4.2.1-0.20171004192657-8fbbd688ea24
gopatch availablevia ghsa
Product: github.com/mattermost/mattermost-serverFixed in: 4.3.0

Vendor Advisories (1)

goGHSA-h564-6gc2-fcc6medium

Mattermost Server allows users with a session ID to revoke another users' session

May 24, 2022

References

mattermost.com / security-updates
Vendor Advisory