{"id":"CVE-2021-40818","aliases":["DEBIAN-CVE-2021-40818","EUVD-2021-27982","GHSA-ppv3-px64-q9mx","UBUNTU-CVE-2021-40818"],"status":"published","title":"scheme/webauthn.c in Glewlwyd SSO server through 2.5.3 has a buffer overflow during FIDO2...","description":"scheme/webauthn.c in Glewlwyd SSO server through 2.5.3 has a buffer overflow during FIDO2 signature validation in webauthn registration.","severity":{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical","assessor":"primary","from":"nvd"},"epss":{"day":"2026-11-12","score":0.01492,"percentile":0.74497,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-120"],"published":"2021-09-08T21:47:32Z","modified":"2026-10-23T18:03:33Z","fixes":[{"ecosystem":"Debian:12","package":"glewlwyd","fixed_in":["2.5.2-3"],"sources":["osv"]},{"ecosystem":"Debian:13","package":"glewlwyd","fixed_in":["2.5.2-3"],"sources":["osv"]}],"affected":[{"source":"osv","ecosystem":"Debian:12","package":"glewlwyd","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.5.2-3"}]}]},{"source":"osv","ecosystem":"Debian:13","package":"glewlwyd","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.5.2-3"}]}]},{"source":"osv","ecosystem":"Ubuntu:18.04:LTS","package":"glewlwyd","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.1-2ubuntu1","1.2.2-1","1.3.1-1"]},{"source":"osv","ecosystem":"Ubuntu:20.04:LTS","package":"glewlwyd","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.4.9-2","1.4.9-3"]},{"source":"osv","ecosystem":"Ubuntu:22.04:LTS","package":"glewlwyd","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.5.2-3","2.6.1-1","2.6.1-1build1"]}],"products":[{"vendor":"glewlwyd_sso_server_project","product":"glewlwyd_sso_server"}],"references":[{"url":"https://github.com/babelouest/glewlwyd/commit/0efd112bb62f566877750ad62ee828bff579b4e2","tags":["x_refsource_MISC","x_transferred","Patch","Third Party Advisory","fix","report"]},{"url":"https://bugs.debian.org/993867","tags":["x_refsource_MISC","x_transferred","Issue Tracking","Mailing List","Third Party Advisory","report"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2021-40818"},{"url":"https://github.com/advisories/GHSA-ppv3-px64-q9mx"},{"url":"https://security-tracker.debian.org/tracker/CVE-2021-40818","tags":["advisory"]},{"url":"https://ubuntu.com/security/CVE-2021-40818","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2021-40818","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2021-40818","description":"scheme/webauthn.c in Glewlwyd SSO server through 2.5.3 has a buffer overflow during FIDO2 signature validation in webauthn registration.","status":"published","published":"2021-09-08T21:47:32Z","modified":"2024-08-04T02:51:07.044Z","updated_at":"2026-11-02T14:33:01.852999Z"}],"euvd":[{"id":"EUVD-2021-27982","description":"scheme/webauthn.c in Glewlwyd SSO server through 2.5.3 has a buffer overflow during FIDO2 signature validation in webauthn registration.","status":"published","published":"2021-09-08T21:47:32Z","modified":"2024-08-04T02:51:07Z","updated_at":"2026-11-03T03:24:19.692229Z"}],"ghsa":[{"id":"GHSA-ppv3-px64-q9mx","title":"scheme/webauthn.c in Glewlwyd SSO server through 2.5.3 has a buffer overflow during FIDO2...","description":"scheme/webauthn.c in Glewlwyd SSO server through 2.5.3 has a buffer overflow during FIDO2 signature validation in webauthn registration.","status":"published","published":"2022-05-24T19:14:08Z","modified":"2023-01-30T05:02:10Z","cwes":["CWE-120"],"updated_at":"2026-11-02T14:46:34.725436Z"}],"nvd":[{"id":"CVE-2021-40818","description":"scheme/webauthn.c in Glewlwyd SSO server through 2.5.3 has a buffer overflow during FIDO2 signature validation in webauthn 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