{"cve":"CVE-2026-66882","nvd":{"published":"2026-08-25T08:18:10.143","modified":"2026-09-01T21:15:00.147","status":"Deferred","description":"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 <%= %> 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.","cvss_v4":{"vector":"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","score":2.1},"cvss_v3":null,"cwes":["CWE-79"],"references":["https://cna.erlef.org/cves/CVE-2026-66882.html","https://github.com/team-alembic/ash_authentication/commit/0bd5199db066be22b2ca1ec8bc6109e5d62e6070","https://github.com/team-alembic/ash_authentication/commit/62719710790a150a9eacab9c0a066e0d122d15be","https://github.com/team-alembic/ash_authentication/security/advisories/GHSA-54fc-x3hv-ffhw","https://osv.dev/vulnerability/EEF-CVE-2026-66882"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:50:17.453294893+00:00"},"epss":{"cve":"CVE-2026-66882","score":0.0075,"percentile":0.54955,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}