{"id":"CVE-2026-94201","revision":"390bbf2f456e485498070b29b261c2dd","records":[{"revision":"390bbf2f456e485498070b29b261c2dd","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-94201","aliases":[],"title":"Filtering an :atom attribute with unsafe_to_atom? can exhaust the BEAM atom table in Ash","description":"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.","state":0,"publishedAt":"2026-10-05T19:19:51.326+00:00","modifiedAt":"2026-10-06T13:41:22.142+00:00","affected":[{"ecosystem":"https://repo.hex.pm","name":"ash","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"collectionURL\": \"https://repo.hex.pm\",\n                    \"cpes\": [\n                        \"cpe:2.3:a:ash-project:ash:*:*:*:*:*:*:*:*\"\n                    ],\n                    \"defaultStatus\": \"unaffected\",\n                    \"modules\": [\n                        \"'Elixir.Ash.Type.Atom'\"\n                    ],\n                    \"packageName\": \"ash\",\n                    \"packageURL\": \"pkg:hex/ash\",\n                    \"product\": \"ash\",\n                    \"programFiles\": [\n                        \"lib/ash/type/atom.ex\"\n                    ],\n                    \"programRoutines\": [\n                        {\n                            \"name\": \"'Elixir.Ash.Type.Atom':cast_value/2\"\n                        }\n                    ],\n                    \"repo\": \"https://github.com/ash-project/ash\",\n                    \"vendor\": \"ash-project\",\n                    \"versions\": [\n                        {\n                            \"lessThan\": \"3.34.3\",\n                            \"status\": \"affected\",\n                            \"version\": \"3.5.1\",\n                            \"versionType\": \"semver\"\n                        }\n                    ]\n                }"},{"ecosystem":"https://github.com","name":"ash-project/ash","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"collectionURL\": \"https://github.com\",\n                    \"cpes\": [\n                        \"cpe:2.3:a:ash-project:ash:*:*:*:*:*:*:*:*\"\n                    ],\n                    \"defaultStatus\": \"unaffected\",\n                    \"modules\": [\n                        \"'Elixir.Ash.Type.Atom'\"\n                    ],\n                    \"packageName\": \"ash-project/ash\",\n                    \"packageURL\": \"pkg:github/ash-project/ash\",\n                    \"product\": \"ash\",\n                    \"programFiles\": [\n                        \"lib/ash/type/atom.ex\"\n                    ],\n                    \"programRoutines\": [\n                        {\n                            \"name\": \"'Elixir.Ash.Type.Atom':cast_value/2\"\n                        }\n                    ],\n                    \"repo\": \"https://github.com/ash-project/ash\",\n                    \"vendor\": \"ash-project\",\n                    \"versions\": [\n                        {\n                            \"lessThan\": \"5282f3f513053628cdd1bf2236ea22d975d934d4\",\n                            \"status\": \"affected\",\n                            \"version\": \"2970ba3bd5d36d6ad04c731ac87385375d457147\",\n                            \"versionType\": \"git\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 4.0","vector":"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","score":8.2,"severity":"HIGH"}],"references":["https://cna.erlef.org/cves/CVE-2026-94201.html","https://osv.dev/vulnerability/EEF-CVE-2026-94201","https://github.com/ash-project/ash/commit/2970ba3bd5d36d6ad04c731ac87385375d457147","https://github.com/ash-project/ash/commit/5282f3f513053628cdd1bf2236ea22d975d934d4"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-94201","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-94201","identifiers":["CVE-2026-94201"]},"retained":false,"historicalAffected":[]}],"coverage":[]}