{"cve":"CVE-2026-6673","nvd":{"published":"2026-06-22T14:17:51.260","modified":"2026-06-23T20:49:21.050","status":"Analyzed","description":"Mattermost versions 11.7.x <= 11.7.0, 11.6.x <= 11.6.2, 11.5.x <= 11.5.5, 10.11.x <= 10.11.17 fail to authenticate Atlassian Connect installed callbacks, allowing a remote unauthenticated attacker to inject a rogue sharedSecret and disrupt the Jira integration via POST to /ac/installed during the pending-install window.. Mattermost Advisory ID: MMSA-2026-00654","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:H/A:H","score":6.4},"cwes":["CWE-306"],"references":["https://mattermost.com/security-updates"],"products":["mattermost:mattermost_server"],"source":"nvd","synced_at":"2026-10-19T22:39:28.638635428+00:00"},"epss":{"cve":"CVE-2026-6673","score":0.00299,"percentile":0.22623,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-jqgv-39mg-7c2r","url":"https://osv.dev/vulnerability/GHSA-jqgv-39mg-7c2r","summary":"Mattermost doesn't authenticate Atlassian Connect installed callbacks, allowing a remote unauthenticated attacker to inject a rogue sharedSecret","modified":"2026-09-28T17:11:11.735586346Z","packages":[{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","purl":"pkg:golang/github.com/mattermost/mattermost-server","ranges":[">=11.7.0 <11.7.1"],"fixed":["11.7.1"]},{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","purl":"pkg:golang/github.com/mattermost/mattermost-server","ranges":[">=11.6.0 <11.6.3"],"fixed":["11.6.3"]},{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","purl":"pkg:golang/github.com/mattermost/mattermost-server","ranges":[">=11.5.0 <11.5.6"],"fixed":["11.5.6"]},{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","purl":"pkg:golang/github.com/mattermost/mattermost-server","ranges":[">=10.11.0 <10.11.18"],"fixed":["10.11.18"]}]},{"id":"GO-2026-6483","url":"https://osv.dev/vulnerability/GO-2026-6483","summary":"Mattermost doesn't authenticate Atlassian Connect installed callbacks, allowing a remote unauthenticated attacker to inject a rogue sharedSecret in github.com/mattermost/mattermost-server","modified":"2026-09-28T17:00:16.000604549Z","packages":[{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","purl":"pkg:golang/github.com/mattermost/mattermost-server","ranges":[">=10.11.0+incompatible <10.11.18+incompatible",">=11.5.0+incompatible <11.5.6+incompatible",">=11.6.0+incompatible <11.6.3+incompatible",">=11.7.0+incompatible <11.7.1+incompatible"],"fixed":["10.11.18+incompatible","11.5.6+incompatible","11.6.3+incompatible","11.7.1+incompatible"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}