4.3

CVE-2017-18889: mattermost mattermost_server Improper Input Validation

CVSS: 4.3v3.1MediumModified
AliasesGHSA-jp57-4x34-5v94GO-2025-4201
Published 19-06-2020Last modified 05-08-2024
Open JSON

Vulnerability summary

CVE-2017-18889 is a medium (CVSS 4.3) Improper Input Validation vulnerability in mattermost mattermost_server. EPSS estimates a 0.67% chance of exploitation in the next 30 days, higher than 51.3% of scored vulnerabilities.

Overall risk
17/100
0100
Low · default modelHow is this calculated?
CVSS score
4.3/10
010
Medium · v3.1 (NVD)
EPSS score
0.67%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 2 · Related 2
OPENSUSE-SU-2026:21483-1SUSE-SU-2026:0037-1

Timeline

  1. 19-06-2020
    PublishedVulnerability first disclosed.
  2. 05-08-2024
    Last modifiedVulnerability information updated.

Description

An issue was discovered in Mattermost Server before 4.3.0, 4.2.1, and 4.1.2. An attacker could create fictive system-message posts via webhooks and slash commands, in the v3 or v4 REST API.

CVSS metrics

3 scores · 2 sources · 2 versions

EPSS trend

Probability

0.67%

Chance of exploitation in the next 30 days

Percentile

51%

Versus all other CVEs

30-day change

0.00 pp

From 0.66% on 21-09-2026

21-09-202621-10-2026
EPSS score
0.67%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Github.com/mattermost1 product
  • mattermost-server< 4.1.2 | ≥ 4.2.0-rc1, < 4.2.1 | ≥ 4.3.0-rc1, < 4.3.0 | ≥ 4.3.0-rc1+incompatible, < 4.3.0+incompatible
Mattermost1 product
  • mattermost_server< 4.1.2 | ≥ 4.2.0, < 4.2.1 | 4.3.0:rc1 | 4.3.0:rc2 | 4.3.0:rc3 | 4.3.0:rc4

2 vendors · 2 products

References

5 links