{"id":"CVE-2026-54894","aliases":["EEF-CVE-2026-54894","EUVD-2026-51915","GHSA-xqch-c77q-rgh5"],"status":"published","title":"Atom-table exhaustion denial of service in Guardian via unbounded atom creation from binary keys","description":"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.","severity":{"version":"4.0","score":6.9,"vector":"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","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-09","score":0.00476,"percentile":0.4142,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-770"],"published":"2026-08-01T18:46:05Z","modified":"2026-10-28T02:31:04Z","fixes":[{"ecosystem":"Hex","package":"guardian","fixed_in":["2.4.1"],"sources":["osv"]}],"affected":[{"source":"osv","ecosystem":"Hex","package":"guardian","ranges":[{"type":"SEMVER","events":[{"introduced":"0.1.0"},{"fixed":"2.4.1"}]}],"versions":["0.1.0","0.1.1","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","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","1.0.0","1.0.0-beta.0","1.0.0-beta.1","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"]}],"products":[{"vendor":"hashgraph","product":"guardian"},{"vendor":"ueberauth","product":"guardian"}],"references":[{"url":"https://github.com/ueberauth/guardian/security/advisories/GHSA-xqch-c77q-rgh5","tags":["vendor-advisory","related","exploit","Exploit","Patch","Vendor Advisory","advisory"]},{"url":"https://cna.erlef.org/cves/CVE-2026-54894.html","tags":["related","Third Party Advisory","web"]},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-54894","tags":["related","Third Party Advisory","web"]},{"url":"https://github.com/ueberauth/guardian/commit/2952657e42e6341a67e6aaad09d8f0b40ae917cb","tags":["patch","Patch","fix"]},{"url":"https://github.com","tags":["web"]},{"url":"https://repo.hex.pm","tags":["web"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/54xxx/CVE-2026-54894.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-54894","tags":["advisory"]},{"url":"https://github.com/ueberauth/guardian","tags":["package"]},{"url":"https://hex.pm/packages/guardian","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-54894","title":"Atom-table exhaustion denial of service in Guardian via unbounded atom creation from binary keys","description":"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.","status":"published","published":"2026-08-01T18:46:05.861Z","modified":"2026-08-03T17:49:54.22Z","cvss":[{"version":"4.0","score":6.9,"vector":"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","level":"medium","assessor":"cna"}],"cwes":["CWE-770"],"updated_at":"2026-11-02T13:38:09.774038Z"}],"euvd":[{"id":"EUVD-2026-51915","description":"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.","status":"published","published":"2026-08-01T18:46:05Z","modified":"2026-08-03T17:49:54Z","cvss":[{"version":"4.0","score":6.9,"vector":"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","level":"medium"}],"updated_at":"2026-11-02T18:02:24.01774Z"}],"nvd":[{"id":"CVE-2026-54894","description":"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.","status":"published","published":"2026-08-01T19:16:41.977Z","modified":"2026-10-23T22:10:00.16Z","cvss":[{"version":"4.0","score":6.9,"vector":"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"medium","assessor":"secondary"},{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"primary"}],"cwes":["CWE-770"],"updated_at":"2026-11-02T14:12:34.290716Z"}],"osv":[{"id":"CVE-2026-54894","title":"Atom-table exhaustion denial of service in Guardian via unbounded atom creation from binary keys","description":"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.","status":"published","published":"2026-08-01T18:46:05.861Z","modified":"2026-10-28T02:31:04.782773801Z","cvss":[{"version":"4.0","score":6.9,"vector":"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","level":"medium"}],"cwes":["CWE-770"],"updated_at":"2026-11-02T15:45:10.818486Z"},{"id":"EEF-CVE-2026-54894","title":"Atom-table exhaustion denial of service in Guardian via unbounded atom creation from binary keys","description":"## 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\\_\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.\n\n## Workarounds\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## Configurations\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.","status":"published","published":"2026-08-01T18:46:05.861Z","modified":"2026-09-08T03:30:09.035963445Z","cvss":[{"version":"4.0","score":6.9,"vector":"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","level":"medium"}],"cwes":["CWE-770"],"updated_at":"2026-11-02T15:46:33.520522Z"}]}}