{"id":"CVE-2026-66882","summary":"Reflected XSS in AshAuthentication confirmation and magic link interaction forms","details":"Improper Neutralization of Input During Web Page Generation (XSS) vulnerability in team-alembic AshAuthentication allows reflected cross-site scripting via the confirmation and magic link interaction forms.\n\nWhen a strategy is configured with require_interaction? set to true, AshAuthentication serves an intermediate HTML page asking the user to confirm the action by submitting a form. Both such pages embed a request parameter directly into a hidden input's value attribute without HTML escaping: lib/ash_authentication/add_ons/confirmation/confirmation_form.html.eex interpolates the confirm parameter, and lib/ash_authentication/strategies/magic_link/sign_in_form.html.eex interpolates the magic link token parameter. These templates are compiled with EEx.function_from_file/3 using plain \u003c%= %\u003e expressions, which perform no escaping, so the parameter is reflected verbatim.\n\nNeither accept handler validates the value before rendering it. AshAuthentication.AddOn.Confirmation.Plug.accept/2 only checks that a confirm key is present, and AshAuthentication.Strategy.MagicLink.Plug.accept/2 reads the parameter directly, so no token signature is verified at this stage and arbitrary attacker-supplied text reaches the template. An unauthenticated attacker can therefore craft a URL whose parameter terminates the attribute and injects markup, for example a quote followed by a \u003cscript\u003e element. Because the accept phase is served over GET, loading the crafted link is sufficient; no form submission or prior authentication is required.\n\nThe injected script executes in the origin of the application embedding AshAuthentication, giving it access to that origin's cookies, session, and same-origin responses. Since these pages are part of the authentication flow, a victim following what appears to be a legitimate confirmation or sign-in link is a plausible target.\n\nThis issue affects ash_authentication: from 4.8.0 before 4.14.2 and from 5.0.0-rc.0 before 5.0.0-rc.13.","aliases":["EEF-CVE-2026-66882","GHSA-54fc-x3hv-ffhw"],"modified":"2026-08-30T11:45:15.687299681Z","published":"2026-08-25T08:03:47.721Z","database_specific":{"cna_assigner":"EEF","cwe_ids":["CWE-79"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/66xxx/CVE-2026-66882.json","unresolved_ranges":[{"extracted_events":[{"introduced":"fe0b4558dbe852fee5d81a460a8355577618a8c8"},{"fixed":"*"}],"source":"AFFECTED_FIELD"}]},"references":[{"type":"WEB","url":"https://cna.erlef.org/cves/CVE-2026-66882.html"},{"type":"WEB","url":"https://github.com"},{"type":"WEB","url":"https://osv.dev/vulnerability/EEF-CVE-2026-66882"},{"type":"WEB","url":"https://repo.hex.pm"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/66xxx/CVE-2026-66882.json"},{"type":"ADVISORY","url":"https://github.com/team-alembic/ash_authentication/security/advisories/GHSA-54fc-x3hv-ffhw"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-66882"},{"type":"FIX","url":"https://github.com/team-alembic/ash_authentication/commit/0bd5199db066be22b2ca1ec8bc6109e5d62e6070"},{"type":"FIX","url":"https://github.com/team-alembic/ash_authentication/commit/62719710790a150a9eacab9c0a066e0d122d15be"},{"type":"PACKAGE","url":"https://github.com/team-alembic/ash_authentication"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/team-alembic/ash_authentication","events":[{"introduced":"cf2095dda5d489ee37166cfce0905f6bd21f4761"},{"fixed":"5a32a74e99d38b58d5b7e94c986c96356d5cd3e3"},{"introduced":"6767fe27eb952e5bc09aa2e5a7d8f96f5a1c424a"},{"fixed":"d1dc61ad0e5034ee3d41dce6cf83eea94dcd46d3"},{"fixed":"0bd5199db066be22b2ca1ec8bc6109e5d62e6070"},{"fixed":"62719710790a150a9eacab9c0a066e0d122d15be"}],"database_specific":{"extracted_events":[{"introduced":"4.8.0"},{"fixed":"4.14.2"},{"introduced":"5.0.0-rc.0"},{"fixed":"5.0.0-rc.13"}],"source":["DESCRIPTION","REFERENCES"]}}],"versions":["v4.14.1","v5.0.0-rc.12","v5.0.0-rc.11","v5.0.0-rc.10","v4.14.0","v4.13.7","5.0.0-rc.9","5.0.0-rc.8","v5.0.0-rc.7","v5.0.0-rc.6","v5.0.0-rc.5","v5.0.0-rc.4","v5.0.0-rc.3","v5.0.0-rc.2","v5.0.0-rc.1","v5.0.0-rc.0","v4.13.6","v4.13.5","v4.13.4","v4.13.3","v4.13.2","v4.13.1","v4.13.0","v4.12.0","v4.11.0","v4.10.0","v4.9.9","v4.9.8","v4.9.7","v4.9.6","v4.9.5","v4.9.4","v4.9.3","v4.9.2","v4.9.1","v4.9.0","v4.8.7","v4.8.5","v4.8.4","v4.8.3","v4.8.2","v4.8.1","v4.8.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-66882.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N"}]}