{"affected":[{"package":{"ecosystem":"Hex","name":"samly","purl":"pkg:hex/samly"},"ranges":[{"events":[{"introduced":"0.3.0"}],"type":"SEMVER"}],"versions":["0.4.0","0.5.0","0.6.0","0.6.1","0.6.2","0.6.3","0.7.0","0.7.1","0.7.2","0.8.0","0.8.1","0.8.2","0.8.3","0.8.4","0.9.0","0.9.1","0.9.2","0.9.3","0.10.0","0.10.1","1.0.0-rc.0","1.0.0-rc.1","1.0.0","1.1.0","1.2.0","1.3.0","1.4.0"]},{"ranges":[{"events":[{"introduced":"8a5bb1b4a4753d05470da2036323477f63cfdf4c"}],"repo":"https://github.com/dropbox/samly","type":"GIT"}]},{"ranges":[{"events":[{"introduced":"8a5bb1b4a4753d05470da2036323477f63cfdf4c"}],"repo":"https://github.com/handnot2/samly","type":"GIT"}]}],"aliases":["CVE-2026-53424"],"credits":[{"name":"Mark Madsen","type":"REPORTER"},{"name":"Jonatan Männchen / EEF","type":"COORDINATOR"}],"database_specific":{"capec_ids":["CAPEC-60"],"cpe_ids":["cpe:2.3:a:dropbox:samly:*:*:*:*:*:*:*:*","cpe:2.3:a:handnot2:samly:*:*:*:*:*:*:*:*"],"cwe_ids":["CWE-294"]},"details":"## Summary\n\nAuthentication Bypass by Capture-replay vulnerability in dropbox samly allows an attacker to authenticate as the subject of a captured SAML assertion by resubmitting it.\n\nSamly.Helper.decode\\_idp\\_auth\\_resp/3 in lib/samly/helper.ex calls esaml\\_sp:validate\\_assertion/2, whose default duplicate detector is a no-op. The /3 arity accepting a DuplicateFun exists in esaml and implements the check, but Samly never calls it and offers no configuration to supply one, so the SAML 2.0 Web Browser SSO Profile requirement that a bearer assertion be used once is unenforced. An attacker holding a valid SAMLResponse obtained from the network, from browser history, or from logs can submit the identical bytes repeatedly until the assertion's NotOnOrAfter passes, each time establishing a session as the assertion's subject.\n\nThis issue affects samly: from 0.3.0 onward.","id":"EEF-CVE-2026-53424","modified":"2026-08-20T18:37:25.117865Z","published":"2026-08-20T17:27:11.115Z","references":[{"type":"WEB","url":"https://cna.erlef.org/cves/CVE-2026-53424.html"},{"type":"PACKAGE","url":"https://hex.pm/packages/samly"}],"related":[],"schema_version":"1.7.3","severity":[{"score":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N","type":"CVSS_V4"}],"summary":"Missing one-time-use enforcement in Samly allows replay of SAML bearer assertions","upstream":[]}