{"id":"CVE-2026-54894","summary":"Atom-table exhaustion denial of service in Guardian via unbounded atom creation from binary keys","details":"Allocation 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_\u003cinput\u003e\", 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.","aliases":["EEF-CVE-2026-54894","GHSA-xqch-c77q-rgh5"],"modified":"2026-08-03T03:30:22.763622768Z","published":"2026-08-01T18:46:05.861Z","database_specific":{"cwe_ids":["CWE-770"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/54xxx/CVE-2026-54894.json","unresolved_ranges":[{"extracted_events":[{"introduced":"7126fa433afc2563fcac0c9aa35193965f8fd5f8"},{"fixed":"2952657e42e6341a67e6aaad09d8f0b40ae917cb"}],"source":"AFFECTED_FIELD"}],"cna_assigner":"EEF"},"references":[{"type":"WEB","url":"https://cna.erlef.org/cves/CVE-2026-54894.html"},{"type":"WEB","url":"https://github.com"},{"type":"WEB","url":"https://osv.dev/vulnerability/EEF-CVE-2026-54894"},{"type":"WEB","url":"https://repo.hex.pm"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/54xxx/CVE-2026-54894.json"},{"type":"ADVISORY","url":"https://github.com/ueberauth/guardian/security/advisories/GHSA-xqch-c77q-rgh5"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-54894"},{"type":"FIX","url":"https://github.com/ueberauth/guardian/commit/2952657e42e6341a67e6aaad09d8f0b40ae917cb"},{"type":"PACKAGE","url":"https://github.com/ueberauth/guardian"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/ueberauth/guardian","events":[{"introduced":"0"},{"fixed":"e6017b492b8ef55e24fd08dea45ce11780d7b4f7"},{"fixed":"2952657e42e6341a67e6aaad09d8f0b40ae917cb"}],"database_specific":{"extracted_events":[{"introduced":"0.1.0"},{"fixed":"2.4.1"}],"source":["DESCRIPTION","REFERENCES"]}}],"versions":["v2.4.0","v2.3.2","v2.3.1","v2.3.0","v2.2.4","v2.2.3","v2.2.2","v2.2.1","v2.1.2","v2.1.1","2.1.0","v2.0.0","v1.2.1","v1.2.0","v1.1.1","v1.1.0","v1.0.1","v1.0.0","v1.0.0-beta.1","v0.14.5","v0.14.4","v0.14.3","v0.14.2","v0.14.1","v0.14.0","v0.13.0","v0.12.0","v0.11.1","v0.10.1","v0.10.0","v0.9.0","v0.8.1"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-54894.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V4","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"}]}