{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-53424", "assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "state": "PUBLISHED", "assignerShortName": "EEF", "dateReserved": "2026-06-09T11:01:47.529Z", "datePublished": "2026-08-20T17:27:11.115Z", "dateUpdated": "2026-08-21T19:42:21.623Z" }, "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": "

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

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

This issue affects samly: from 0.3.0 onward.

" }, { "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": { "orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "shortName": "EEF", "dateUpdated": "2026-08-20T18:37:24.439Z" }, "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" }, "adp": [ { "metrics": [ { "other": { "type": "ssvc", "content": { "timestamp": "2026-08-21T19:41:30.269903Z", "id": "CVE-2026-53424", "options": [ { "Exploitation": "none" }, { "Automatable": "yes" }, { "Technical Impact": "total" } ], "role": "CISA Coordinator", "version": "2.0.3" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-08-21T19:42:21.623Z" } } ] } }