Mattermost Server exposes team creator's e-mail address to other members

published 2020-06-19 6y ago modified 2026-06-17 4mo ago also GHSA-35c4-5qfp-wxj6 , GO-2025-4199 , EUVD-2017-9977

cvss: 5.3; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 0.9%; EPSS 0.9% chance of exploitation in 30 days, percentile 60%
public exploits: 0; none known

An issue was discovered in Mattermost Server before 4.3.0, 4.2.1, and 4.1.2. It discloses the team creator's e-mail address to members.

Patch / fix

fixed in 2 distros 2

go github.com/mattermost/mattermost-server 4.1.2, 4.1.2+incompatible, 4.2.1, 4.2.1+incompatible, 4.3.0, 4.3.0+incompatible
mattermost mattermost_server 4.1.2, 4.2.1

suse opensuse

govulncheck-vulndb openSUSE Leap 15.6 0.0.20251230T014957-150000.1.134.1

suse advisories SUSE-SU-2026:0037-1

govulncheck-vulndb openSUSE Leap 16.0 0.0.20260723T184607-160000.1.1

opensuse advisories openSUSE-SU-2026:21483-1

Is CVE-2017-18887 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Exploit prediction

0.93% chance of exploitation in the next 30 days, higher than 60% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by	version	score	vector
NVD	3.1	5.3	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
NVD	2.0	5.0	AV:N/AC:L/Au:N/C:P/I:N/A:N
GitHub	3.1	5.3	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Affected packages

ecosystem	package	affected	fixed in
go	github.com/mattermost/mattermost-server	<4.1.2 >=4.2.0-rc1, <4.2.1 >=4.3.0-rc1, <4.3.0 <4.1.2+incompatible >=4.2.0-rc1+incompatible, <4.2.1+incompatible >=4.3.0-rc1+incompatible, <4.3.0+incompatible	4.1.2 4.2.1 4.3.0 4.1.2+incompatible 4.2.1+incompatible 4.3.0+incompatible

Classification

Weakness

CWE-200 Exposure of Sensitive Information to an Unauthorized Actor

References

mattermost.com /security-updates/
vendor-advisory
nvd.nist.gov /vuln/detail/CVE-2017-18887
advisory
github.com /mattermost/mattermost
package
mattermost.com /security-updates
web
github.com /advisories/GHSA-35c4-5qfp-wxj6
advisory

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.