{"affected":[{"package":{"ecosystem":"Hex","name":"ash_authentication","purl":"pkg:hex/ash_authentication"},"ranges":[{"events":[{"introduced":"4.8.0"},{"fixed":"4.14.2"}],"type":"SEMVER"},{"events":[{"introduced":"5.0.0-rc.0"},{"fixed":"5.0.0-rc.13"}],"type":"SEMVER"}],"versions":["4.8.0","4.8.1","4.8.2","4.8.3","4.8.5","4.8.6","4.8.7","4.9.0","4.9.1","4.9.2","4.9.3","4.9.4","4.9.5","4.9.6","4.9.7","4.9.8","4.9.9","4.10.0","4.11.0","4.12.0","4.13.0","4.13.1","4.13.2","4.13.3","4.13.4","4.13.5","4.13.6","4.13.7","4.14.0","4.14.1","5.0.0-rc.0","5.0.0-rc.1","5.0.0-rc.2","5.0.0-rc.3","5.0.0-rc.4","5.0.0-rc.5","5.0.0-rc.6","5.0.0-rc.7","5.0.0-rc.8","5.0.0-rc.9","5.0.0-rc.10","5.0.0-rc.11","5.0.0-rc.12"]},{"ranges":[{"events":[{"introduced":"fe0b4558dbe852fee5d81a460a8355577618a8c8"},{"fixed":"62719710790a150a9eacab9c0a066e0d122d15be"},{"fixed":"0bd5199db066be22b2ca1ec8bc6109e5d62e6070"}],"repo":"https://github.com/team-alembic/ash_authentication","type":"GIT"}]}],"aliases":["GHSA-54fc-x3hv-ffhw","CVE-2026-66882"],"credits":[{"name":"Arpit Jain","type":"FINDER"},{"name":"James Harton","type":"REMEDIATION_DEVELOPER"},{"name":"Jonatan Männchen / EEF","type":"COORDINATOR"}],"database_specific":{"capec_ids":["CAPEC-591"],"cpe_ids":["cpe:2.3:a:team-alembic:ash_authentication:*:*:*:*:*:*:*:*"],"cwe_ids":["CWE-79"]},"details":"## Summary\n\nImproper 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 `<%= %>` 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 `<script>` 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.\n\n## Configurations\n\nOnly strategies configured with `require_interaction?` set to `true` are affected. This option defaults to `false`, and when it is disabled the vulnerable accept route is not registered at all, so the affected pages cannot be reached.\n\nThe option is not obscure: AshAuthentication's own documentation for the confirmation add-on advises that applications using AshAuthenticationPhoenix should enable it, so the affected configuration is a documented and recommended deployment rather than an unusual one.\n\nAt least one of the following must be configured with `require_interaction? true`:\n\n- the `confirmation` add-on, which serves the affected confirmation accept form; or\n- the `magic_link` strategy, which serves the affected sign-in accept form.","id":"EEF-CVE-2026-66882","modified":"2026-09-08T04:15:00.988270Z","published":"2026-08-25T08:03:47.721Z","references":[{"type":"ADVISORY","url":"https://github.com/team-alembic/ash_authentication/security/advisories/GHSA-54fc-x3hv-ffhw"},{"type":"WEB","url":"https://cna.erlef.org/cves/CVE-2026-66882.html"},{"type":"FIX","url":"https://github.com/team-alembic/ash_authentication/commit/62719710790a150a9eacab9c0a066e0d122d15be"},{"type":"FIX","url":"https://github.com/team-alembic/ash_authentication/commit/0bd5199db066be22b2ca1ec8bc6109e5d62e6070"},{"type":"PACKAGE","url":"https://hex.pm/packages/ash_authentication"}],"related":[],"schema_version":"1.7.3","severity":[{"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","type":"CVSS_V4"}],"summary":"Reflected XSS in AshAuthentication confirmation and magic link interaction forms","upstream":[]}