{"id":"CVE-2026-94201","summary":"Filtering an :atom attribute with unsafe_to_atom? can exhaust the BEAM atom table in Ash","details":"Ash 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.","aliases":["EEF-CVE-2026-94201"],"modified":"2026-10-10T02:47:31.662300342Z","published":"2026-10-05T19:19:51.326Z","database_specific":{"cwe_ids":["CWE-770"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/94xxx/CVE-2026-94201.json","cna_assigner":"EEF"},"references":[{"type":"WEB","url":"https://github.com"},{"type":"WEB","url":"https://osv.dev/vulnerability/EEF-CVE-2026-94201"},{"type":"WEB","url":"https://repo.hex.pm"},{"type":"ADVISORY","url":"https://cna.erlef.org/cves/CVE-2026-94201.html"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/94xxx/CVE-2026-94201.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-94201"},{"type":"FIX","url":"https://github.com/ash-project/ash/commit/2970ba3bd5d36d6ad04c731ac87385375d457147"},{"type":"FIX","url":"https://github.com/ash-project/ash/commit/5282f3f513053628cdd1bf2236ea22d975d934d4"},{"type":"PACKAGE","url":"https://github.com/ash-project/ash"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/ash-project/ash","events":[{"introduced":"2970ba3bd5d36d6ad04c731ac87385375d457147"},{"fixed":"5282f3f513053628cdd1bf2236ea22d975d934d4"},{"introduced":"c5d533ea0331333456bd768a0b23660224efcc9e"},{"fixed":"8df3aeabbf8fbf801d4bcb7bce2e81bea550fd10"}],"database_specific":{"extracted_events":[{"introduced":"3.5.1"},{"fixed":"3.34.3"}],"source":"AFFECTED_FIELD"}}],"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://storage.googleapis.com/cve-osv-conversion/osv-output/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"}]}