{"cve":"CVE-2026-2455","nvd":{"published":"2026-03-16T15:16:22.277","modified":"2026-06-17T10:30:59.067","status":"Analyzed","description":"Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to canonicalize IPv4-mapped IPv6 addresses before reserved IP validation which allows an attacker to perform SSRF attacks against internal services via IPv4-mapped IPv6 literals (e.g., [::ffff:127.0.0.1]).. Mattermost Advisory ID: MMSA-2026-00585","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N","score":4.3},"cwes":["CWE-918"],"references":["https://mattermost.com/security-updates"],"products":["mattermost:mattermost_server"],"source":"nvd","synced_at":"2026-10-19T22:26:19.218427112+00:00"},"epss":{"cve":"CVE-2026-2455","score":0.00168,"percentile":0.06102,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-gqv7-j2j8-qmwq","url":"https://osv.dev/vulnerability/GHSA-gqv7-j2j8-qmwq","summary":"Mattermost fails to canonicalize IPv4-mapped IPv6 addresses before reserved IP validation","modified":"2026-03-23T18:56:08.125706Z","packages":[{"ecosystem":"Go","name":"github.com/mattermost/mattermost/server/v8","purl":"pkg:golang/github.com/mattermost/mattermost/server/v8","ranges":["<8.0.0-20260129133647-5d787969c2d5"],"fixed":["8.0.0-20260129133647-5d787969c2d5"]},{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","purl":"pkg:golang/github.com/mattermost/mattermost-server","ranges":["<5.3.2-0.20260129133647-5d787969c2d5"],"fixed":["5.3.2-0.20260129133647-5d787969c2d5"]},{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","purl":"pkg:golang/github.com/mattermost/mattermost-server","ranges":[">=10.11.0-rc1 <10.11.11"],"fixed":["10.11.11"]},{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","purl":"pkg:golang/github.com/mattermost/mattermost-server","ranges":[">=11.2.0-rc1 <11.2.3"],"fixed":["11.2.3"]},{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","purl":"pkg:golang/github.com/mattermost/mattermost-server","ranges":[">=11.3.0-rc1 <11.3.1"],"fixed":["11.3.1"]}]},{"id":"GO-2026-4746","url":"https://osv.dev/vulnerability/GO-2026-4746","summary":"Mattermost fails to canonicalize IPv4-mapped IPv6 addresses before reserved IP validation in github.com/mattermost/mattermost-server","modified":"2026-03-23T18:45:17.812647Z","packages":[{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","purl":"pkg:golang/github.com/mattermost/mattermost-server","ranges":[">=10.11.0-rc1+incompatible <10.11.11+incompatible",">=11.2.0-rc1+incompatible <11.2.3+incompatible",">=11.3.0-rc1+incompatible <11.3.1+incompatible"],"fixed":["10.11.11+incompatible","11.2.3+incompatible","11.3.1+incompatible"]},{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server/v5","purl":"pkg:golang/github.com/mattermost/mattermost-server/v5","ranges":["all versions"],"fixed":[]},{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server/v6","purl":"pkg:golang/github.com/mattermost/mattermost-server/v6","ranges":["all versions"],"fixed":[]},{"ecosystem":"Go","name":"github.com/mattermost/mattermost/server/v8","purl":"pkg:golang/github.com/mattermost/mattermost/server/v8","ranges":["<8.0.0-20260129133647-5d787969c2d5"],"fixed":["8.0.0-20260129133647-5d787969c2d5"]}]}],"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."]}