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Fencer Intel
critical 9.8

CVE-2017-18900 json

Mattermost Server is vulnerable CSV Injection

published 2020-06-19 6 y ago modified 2026-06-17 4 mo ago also GHSA-8q4v-35v6-g8wr , GO-2026-4303 , EUVD-2017-9990

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.3%
EPSS 1.3% chance of exploitation in 30 days, percentile 70%
public exploits
0
none known

Summary

An issue was discovered in Mattermost Server before 4.1.0, 4.0.4, and 3.10.3. It allows CSV injection via a compliance report.

Patch / fix

  • go github.com/mattermost/mattermost-server 3.10.3, 3.10.3+incompatible, 4.0.3, 4.0.3+incompatible
  • mattermost mattermost_server 3.10.3, 4.0.4
  • govulncheck-vulndb openSUSE Leap 15.6 0.0.20260114T191543-150000.1.137.1

suse advisories SUSE-SU-2026:0142-1

  • govulncheck-vulndb openSUSE Leap 16.0 0.0.20260723T184607-160000.1.1

opensuse advisories openSUSE-SU-2026:21483-1

Exploit prediction

1.30% chance of exploitation in the next 30 days, higher than 70% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P
GitHub 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
go github.com/mattermost/mattermost-server
<3.10.3
>=4.0.0, <4.0.3
<3.10.3+incompatible
>=4.0.0+incompatible, <4.0.3+incompatible
3.10.3
4.0.3
3.10.3+incompatible
4.0.3+incompatible

Classification

Weakness
  • CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component
  • CWE-1236 Improper Neutralization of Formula Elements in a CSV File

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.