CVE-2017-18909 json
Mattermost Server SAML implementation does not require encryption or signature verification as default
published 2020-06-19 6 y ago modified 2026-06-17 4 mo ago also GHSA-r6j5-fqx9-7qv9 , GO-2026-4478 , EUVD-2017-9999
- cvss
- 7.5
- version 3.1, NVD
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.7%
- EPSS 0.7% chance of exploitation in 30 days, percentile 51%
- public exploits
- 0
- none known
Summary
An issue was discovered in Mattermost Server before 3.9.0 when SAML is used. Encryption and signature verification are not mandatory.
Patch / fix
- go github.com/mattermost/mattermost-server 3.8.1-0.20170504181128-4f074fed0d65
- mattermost mattermost_server 3.9.0
- govulncheck-vulndb openSUSE Leap 15.6 0.0.20260226T182644-150000.1.149.1
suse advisories SUSE-SU-2026:0757-1
- govulncheck-vulndb openSUSE Leap 16.0 0.0.20260723T184607-160000.1.1
opensuse advisories openSUSE-SU-2026:21483-1
Exploit prediction
0.66% chance of exploitation in the next 30 days, higher than 51% of all scored CVEs (FIRST EPSS, 2026-11-09).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| NVD | 3.1 | 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N |
| NVD | 2.0 | 4.3 | AV:N/AC:M/Au:N/C:P/I:N/A:N |
| GitHub | 3.1 | 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| go | github.com/mattermost/mattermost-server | <3.8.1-0.20170504181128-4f074fed0d65 all versions |
3.8.1-0.20170504181128-4f074fed0d65 |
Classification
References
-
github.com
/mattermost/mattermost/commit/4f074fed0d653a28779ac586e418341232d43e95
web
-
mattermost.com
/security-updates/
vendor-advisory
-
nvd.nist.gov
/vuln/detail/CVE-2017-18909
advisory
-
github.com
/mattermost/mattermost
package
-
mattermost.com
/security-updates
web
-
github.com
/advisories/GHSA-r6j5-fqx9-7qv9
advisory
Sources
- CVE List CVE-2017-18909
- GitHub Advisory GHSA-r6j5-fqx9-7qv9
- NVD CVE-2017-18909
- OSV GO-2026-4478
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.