{"containers":{"cna":{"affected":[{"collectionURL":"https://repo.hex.pm","cpes":["cpe:2.3:a:dropbox:samly:*:*:*:*:*:*:*:*"],"defaultStatus":"unaffected","modules":["'Elixir.Samly.Helper'"],"packageName":"samly","packageURL":"pkg:hex/samly","product":"samly","programFiles":["lib/samly/helper.ex"],"programRoutines":[{"name":"'Elixir.Samly.Helper':decode_idp_auth_resp/3"}],"repo":"https://github.com/dropbox/samly","vendor":"dropbox","versions":[{"lessThan":"*","status":"affected","version":"0.3.0","versionType":"semver"}]},{"collectionURL":"https://github.com","cpes":["cpe:2.3:a:dropbox:samly:*:*:*:*:*:*:*:*"],"defaultStatus":"unaffected","modules":["'Elixir.Samly.Helper'"],"packageName":"dropbox/samly","packageURL":"pkg:github/dropbox/samly","product":"samly","programFiles":["lib/samly/helper.ex"],"programRoutines":[{"name":"'Elixir.Samly.Helper':decode_idp_auth_resp/3"}],"repo":"https://github.com/dropbox/samly","vendor":"dropbox","versions":[{"lessThan":"*","status":"affected","version":"8a5bb1b4a4753d05470da2036323477f63cfdf4c","versionType":"git"}]},{"collectionURL":"https://github.com","cpes":["cpe:2.3:a:handnot2:samly:*:*:*:*:*:*:*:*"],"defaultStatus":"unaffected","modules":["'Elixir.Samly.Helper'"],"packageName":"handnot2/samly","packageURL":"pkg:github/handnot2/samly","product":"samly","programFiles":["lib/samly/helper.ex"],"programRoutines":[{"name":"'Elixir.Samly.Helper':decode_idp_auth_resp/3"}],"repo":"https://github.com/handnot2/samly","vendor":"handnot2","versions":[{"lessThan":"*","status":"affected","version":"8a5bb1b4a4753d05470da2036323477f63cfdf4c","versionType":"git"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:a:dropbox:samly:*:*:*:*:*:*:*:*","versionStartIncluding":"0.3.0","vulnerable":true},{"criteria":"cpe:2.3:a:handnot2:samly:*:*:*:*:*:*:*:*","versionStartIncluding":"0.3.0","vulnerable":true}],"negate":false,"operator":"OR"}],"operator":"AND"}],"credits":[{"lang":"en","type":"reporter","value":"Mark Madsen"},{"lang":"en","type":"coordinator","value":"Jonatan Männchen / EEF"}],"descriptions":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"<p>Authentication Bypass by Capture-replay vulnerability in dropbox samly allows an attacker to authenticate as the subject of a captured SAML assertion by resubmitting it.</p>\n<p><code>Samly.Helper.decode_idp_auth_resp/3</code> in <code>lib/samly/helper.ex</code> calls <code>esaml_sp:validate_assertion/2</code>, whose default duplicate detector is a no-op. The <code>/3</code> arity accepting a <code>DuplicateFun</code> exists in <code>esaml</code> 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 <code>SAMLResponse</code> obtained from the network, from browser history, or from logs can submit the identical bytes repeatedly until the assertion's <code>NotOnOrAfter</code> passes, each time establishing a session as the assertion's subject.</p>\n<p>This issue affects samly: from 0.3.0 onward.</p>"},{"base64":false,"type":"text/markdown","value":"Authentication 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\n`Samly.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."}],"value":"Authentication 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."}],"impacts":[{"capecId":"CAPEC-60","descriptions":[{"lang":"en","value":"CAPEC-60 Reusing Session IDs (aka Session Replay)"}]}],"metrics":[{"cvssV4_0":{"Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","Safety":"NOT_DEFINED","attackComplexity":"LOW","attackRequirements":"PRESENT","attackVector":"NETWORK","baseScore":9.1,"baseSeverity":"CRITICAL","privilegesRequired":"NONE","providerUrgency":"NOT_DEFINED","subAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","userInteraction":"NONE","valueDensity":"NOT_DEFINED","vectorString":"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","version":"4.0","vulnAvailabilityImpact":"NONE","vulnConfidentialityImpact":"HIGH","vulnIntegrityImpact":"HIGH","vulnerabilityResponseEffort":"NOT_DEFINED"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-294","description":"CWE-294 Authentication Bypass by Capture-replay","lang":"en","type":"CWE"}]}],"providerMetadata":{"dateUpdated":"2026-08-20T18:37:24.439Z","orgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","shortName":"EEF"},"references":[{"tags":["related","third-party-advisory"],"url":"https://cna.erlef.org/cves/CVE-2026-53424.html"},{"tags":["related"],"url":"https://osv.dev/vulnerability/EEF-CVE-2026-53424"}],"source":{"discovery":"UNKNOWN"},"title":"Missing one-time-use enforcement in Samly allows replay of SAML bearer assertions"}},"cveMetadata":{"assignerOrgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","assignerShortName":"EEF","cveId":"CVE-2026-53424","datePublished":"2026-08-20T17:27:11.115Z","dateReserved":"2026-06-09T11:01:47.529Z","dateUpdated":"2026-08-20T18:37:24.439Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"}