{"affected":[{"package":{"ecosystem":"Hex","name":"guardian","purl":"pkg:hex/guardian"},"ranges":[{"events":[{"introduced":"0.1.0"},{"fixed":"2.4.1"}],"type":"SEMVER"}],"versions":["0.1.0","0.1.1","0.2.0","0.3.0","0.3.1","0.4.0","0.4.1","0.5.0","0.5.2","0.6.0","0.6.1","0.6.2","0.6.3","0.7.0","0.7.1","0.7.2","0.7.4","0.8.0","0.8.1","0.9.0","0.9.1","0.10.0","0.10.1","0.11.1","0.12.0","0.13.0","0.14.0","0.14.1","0.14.2","0.14.3","0.14.4","0.14.5","0.14.6","1.0.0-beta.0","1.0.0-beta.1","1.0.0","1.0.1","1.1.0","1.1.1","1.2.0","1.2.1","2.0.0","2.1.1","2.1.2","2.2.0","2.2.1","2.2.2","2.2.3","2.2.4","2.3.0","2.3.1","2.3.2","2.4.0"]},{"ranges":[{"events":[{"introduced":"7126fa433afc2563fcac0c9aa35193965f8fd5f8"},{"fixed":"2952657e42e6341a67e6aaad09d8f0b40ae917cb"}],"repo":"https://github.com/ueberauth/guardian","type":"GIT"}]}],"aliases":["GHSA-xqch-c77q-rgh5","CVE-2026-54894"],"credits":[{"name":"Peter Ullrich","type":"FINDER"},{"name":"Yordis Prieto","type":"REMEDIATION_DEVELOPER"},{"name":"Jonatan Männchen / EEF","type":"ANALYST"}],"database_specific":{"capec_ids":["CAPEC-130"],"cpe_ids":["cpe:2.3:a:ueberauth:guardian:*:*:*:*:*:*:*:*"],"cwe_ids":["CWE-770"]},"details":"## Summary\n\nAllocation of Resources Without Limits or Throttling in ueberauth guardian allows denial of service via unbounded atom creation from attacker-influenced binary input.\n\nGuardian.Plug.Keys derives connection and session namespace keys by passing arbitrary binaries to String.to\\_atom/1. base\\_key/1 in lib/guardian/plug/keys.ex converts any binary into the atom :\"guardian\\_<input>\", and the derived helpers claims\\_key/1, resource\\_key/1, and token\\_key/1 create a second atom on top of that. key\\_from\\_other/1 likewise converts a regex-captured binary through String.to\\_atom/1. The public specs advertise String.t() as a valid argument, so passing a string is documented usage, and higher-level entry points such as Guardian.Plug.current\\_token(conn, key: key) thread the caller-supplied key straight into these functions.\n\nString.to\\_atom/1 creates a brand-new atom for every previously unseen binary, atoms are never garbage collected, and the BEAM atom table is fixed at roughly 1,048,576 entries by default. An application that routes attacker-influenced data (a tenant identifier, header, or other request input) into a Guardian key therefore mints one permanent atom per distinct value. A modest stream of varied, unauthenticated input permanently consumes the atom table and crashes the BEAM node, taking down every application running on it.\n\nThis issue affects guardian: from 0.1.0 before 2.4.1.\n\n## Workaround\n\nDo not derive Guardian keys from untrusted input. Use a fixed, hardcoded set of namespace keys, or validate the value against a bounded allowlist of known keys, before passing it as the :key option.\n\n## Configuration\n\nOnly applications that derive a Guardian key (the conn/session namespace) from attacker-influenced data are exploitable. This is the case when a caller-supplied value such as a tenant identifier, request header, or other request input is passed as the :key option to entry points like Guardian.Plug.current\\_token/2. Applications that use a static namespace (the default :default key or hardcoded atoms) are not affected.","id":"EEF-CVE-2026-54894","modified":"2026-08-01T18:46:05.861Z","published":"2026-08-01T18:46:05.861Z","references":[{"type":"ADVISORY","url":"https://github.com/ueberauth/guardian/security/advisories/GHSA-xqch-c77q-rgh5"},{"type":"WEB","url":"https://cna.erlef.org/cves/CVE-2026-54894.html"},{"type":"FIX","url":"https://github.com/ueberauth/guardian/commit/2952657e42e6341a67e6aaad09d8f0b40ae917cb"},{"type":"PACKAGE","url":"https://hex.pm/packages/guardian"}],"related":[],"schema_version":"1.7.3","severity":[{"score":"CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H","type":"CVSS_V4"}],"summary":"Atom-table exhaustion denial of service in Guardian via unbounded atom creation from binary keys","upstream":[]}