{"id":"EEF-CVE-2026-94201","summary":"Filtering an :atom attribute with unsafe_to_atom? can exhaust the BEAM atom table in Ash","details":"## Summary\n\nAsh stores `:atom`-typed attributes as strings and compares them as strings. When such an attribute is referenced in a filter, the comparison value is coerced through `Ash.Type.Atom`. Because the type defined no `coerce/2` callback, coercion fell back to the default (`cast_input/2`), which calls `String.to_atom/1` when the attribute is configured with the `unsafe_to_atom?: true` constraint.\n\nFiltering such an attribute with attacker-controlled strings therefore interned a new, permanent atom for every distinct value. Atoms are never garbage collected and the BEAM caps the atom table, so an actor who can supply filter values for a public, filterable `:atom` attribute declared with `unsafe_to_atom?: true` can exhaust the atom table and crash the node (denial of service). AshPaperTrail is a notable example: its version resources expose a public, filterable `version_action_name` atom attribute with `unsafe_to_atom?: true` by default.\n\nThe fix adds a `coerce/2` to `Ash.Type.Atom` that never interns atoms — a comparison value is left as a string, since the type is stored and compared as a string. Setting the attribute from action input (`cast_input/2`, which still honors `unsafe_to_atom?`) is unchanged.\n\nThis issue affects ash: from 3.5.1 before 3.34.3.\n\n## Configurations\n\nReachable only when an application exposes a public, filterable `:atom` attribute declared with the `unsafe_to_atom?: true` constraint, and an actor can supply filter values for it (for example through AshGraphql, AshJsonApi, or `Ash.Query.filter_input/2`). AshPaperTrail's version resources ship such an attribute (`version_action_name`) by default.","aliases":["CVE-2026-94201"],"modified":"2026-10-05T19:30:54.581895329Z","published":"2026-10-05T19:19:51.326Z","database_specific":{"capec_ids":["CAPEC-130"],"cpe_ids":["cpe:2.3:a:ash-project:ash:*:*:*:*:*:*:*:*"],"cwe_ids":["CWE-770"]},"references":[{"type":"WEB","url":"https://cna.erlef.org/cves/CVE-2026-94201.html"},{"type":"WEB","url":"https://github.com/ash-project/ash/commit/2970ba3bd5d36d6ad04c731ac87385375d457147"},{"type":"FIX","url":"https://github.com/ash-project/ash/commit/5282f3f513053628cdd1bf2236ea22d975d934d4"},{"type":"PACKAGE","url":"https://hex.pm/packages/ash"}],"affected":[{"package":{"name":"ash","ecosystem":"Hex","purl":"pkg:hex/ash"},"ranges":[{"type":"SEMVER","events":[{"introduced":"3.5.1"},{"fixed":"3.34.3"}]}],"versions":["3.10.0","3.10.1","3.11.0","3.11.1","3.11.2","3.11.3","3.12.0","3.13.0","3.13.1","3.13.2","3.14.0","3.14.1","3.15.0","3.16.0","3.17.0","3.17.1","3.18.0","3.19.0","3.19.1","3.19.2","3.19.3","3.20.0","3.21.0","3.21.1","3.21.2","3.21.3","3.22.0","3.22.1","3.22.2","3.23.0","3.23.1","3.24.0","3.24.1","3.24.2","3.24.3","3.24.4","3.24.5","3.24.6","3.24.7","3.25.0","3.25.1","3.25.2","3.26.0","3.27.0","3.27.1","3.27.2","3.27.3","3.27.4","3.27.5","3.27.6","3.27.7","3.27.8","3.28.0","3.29.0","3.29.1","3.29.2","3.29.3","3.30.0","3.30.1","3.31.0","3.31.1","3.31.2","3.31.3","3.32.0","3.32.1","3.32.2","3.32.3","3.33.0","3.33.1","3.33.10","3.33.11","3.33.2","3.33.3","3.33.4","3.33.5","3.33.6","3.33.7","3.33.8","3.33.9","3.34.0","3.34.1","3.34.2","3.5.1","3.5.10","3.5.11","3.5.12","3.5.13","3.5.14","3.5.15","3.5.16","3.5.17","3.5.18","3.5.19","3.5.2","3.5.20","3.5.21","3.5.22","3.5.23","3.5.24","3.5.25","3.5.26","3.5.27","3.5.28","3.5.29","3.5.3","3.5.30","3.5.31","3.5.32","3.5.33","3.5.34","3.5.35","3.5.36","3.5.37","3.5.38","3.5.39","3.5.4","3.5.40","3.5.41","3.5.42","3.5.43","3.5.5","3.5.6","3.5.7","3.5.8","3.5.9","3.6.0","3.6.1","3.6.2","3.6.3","3.7.0","3.7.1","3.7.2","3.7.3","3.7.4","3.7.5","3.7.6","3.8.0","3.9.0"],"database_specific":{"source":"https://cna.erlef.org/osv/EEF-CVE-2026-94201.json"}},{"ranges":[{"type":"GIT","repo":"https://github.com/ash-project/ash","events":[{"introduced":"2970ba3bd5d36d6ad04c731ac87385375d457147"},{"fixed":"5282f3f513053628cdd1bf2236ea22d975d934d4"}]}],"versions":["v3.34.2","v3.34.1","v3.34.0","v3.33.11","v3.33.10","v3.33.9","v3.33.7","v3.33.6","v3.33.5","v3.33.4","v3.33.3","v3.33.2","v3.33.1","v3.32.3","v3.32.2","v3.32.1","v3.31.3","v3.31.2","v3.31.1","v3.31.0","v3.30.1","v3.30.0","v3.29.3","v3.29.2","v3.29.1","v3.29.0","v3.28.0","v3.27.8","v3.27.7","v3.27.6","v3.27.4","v3.27.3","v3.27.2","v3.27.1","v3.27.0","v3.26.0","v3.25.2","v3.25.1","v3.25.0","v3.24.7","v3.24.6","v3.24.5","v3.24.4","v3.24.3","v3.24.2","v3.24.1","v3.24.0","v3.23.1","v3.23.0","v3.22.2","v3.22.1","v3.22.0","v3.21.3","v3.21.2","v3.21.1","v3.21.0","v3.20.0","v3.19.3","v3.19.2","v3.19.1","v3.19.0","v3.18.0","v3.17.1","v3.17.0","v3.16.0","v3.15.0","v3.14.1","v3.14.0","v3.13.2","v3.13.1","v3.13.0","v3.12.0","v3.11.3","v3.11.2","v3.11.1","v3.11.0","v3.10.1","v3.10.0","v3.9.0","v3.8.0","v3.7.6","v3.7.5","v3.7.4","v3.7.3","v3.7.2","v3.7.1","v3.7.0","v3.6.3","v3.6.2","v3.6.1","v3.6.0","v3.5.43","v3.5.42","v3.5.41","v3.5.39","v3.5.38","v3.5.37","v3.5.36","v3.5.35","v3.5.33","v3.5.32","v3.5.31","v3.5.30","v3.5.29","v3.5.28","v3.5.27","v3.5.26","v3.5.25","v3.5.24","v3.5.23","v3.5.22","v3.5.21","v3.5.19","v3.5.18","v3.5.17","v3.5.16","v3.5.15","v3.5.14","v3.5.13","v3.5.12","v3.5.11","v3.5.10","v3.5.8","v3.5.7","v3.5.6","v3.5.5","v3.5.4","v3.5.3","v3.5.2","v3.5.1"],"database_specific":{"source":"https://cna.erlef.org/osv/EEF-CVE-2026-94201.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"}],"credits":[{"name":"Quinn Wilton","type":"FINDER"},{"name":"Quinn Wilton","type":"REPORTER"},{"name":"Zach Daniel / Ash Project","type":"REMEDIATION_DEVELOPER"},{"name":"Jonatan Männchen / EEF","type":"COORDINATOR"}]}