{"id":"CVE-2026-94201","state":"PUBLISHED","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.","publishedAt":"2026-10-05T19:19:51.326Z","updatedAt":"2026-10-06T13:41:22.142Z","severity":{"score":8.2,"label":"High","version":"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","source":"EEF"},"assigner":"EEF","products":["ash-project ash"],"affected":[{"vendor":"ash-project","product":"ash","packageName":"ash","packageURL":"pkg:hex/ash","defaultStatus":"unaffected","versions":[{"version":"3.5.1","status":"affected","lessThan":"3.34.3","versionType":"semver"}],"collectionURL":"https://repo.hex.pm","cpes":["cpe:2.3:a:ash-project:ash:*:*:*:*:*:*:*:*"],"modules":["'Elixir.Ash.Type.Atom'"],"programFiles":["lib/ash/type/atom.ex"],"programRoutines":[{"name":"'Elixir.Ash.Type.Atom':cast_value/2"}],"repo":"https://github.com/ash-project/ash"},{"vendor":"ash-project","product":"ash","packageName":"ash-project/ash","packageURL":"pkg:github/ash-project/ash","defaultStatus":"unaffected","versions":[{"version":"2970ba3bd5d36d6ad04c731ac87385375d457147","status":"affected","lessThan":"5282f3f513053628cdd1bf2236ea22d975d934d4","versionType":"git"}],"collectionURL":"https://github.com","cpes":["cpe:2.3:a:ash-project:ash:*:*:*:*:*:*:*:*"],"modules":["'Elixir.Ash.Type.Atom'"],"programFiles":["lib/ash/type/atom.ex"],"programRoutines":[{"name":"'Elixir.Ash.Type.Atom':cast_value/2"}],"repo":"https://github.com/ash-project/ash"}],"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"],"weaknesses":["CWE-770"],"ingestedAt":"2026-10-29T20:13:34.582Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/94xxx/CVE-2026-94201.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-94201","state":"PUBLISHED","datePublished":"2026-10-05T19:19:51.326Z","dateUpdated":"2026-10-06T13:41:22.142Z","assignerShortName":"EEF","assignerOrgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","dateReserved":"2026-09-24T09:15:02.216Z"},"containers":{"cna":{"title":"Filtering an :atom attribute with unsafe_to_atom? can exhaust the BEAM atom table in Ash","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"ash-project","product":"ash","packageName":"ash","packageURL":"pkg:hex/ash","defaultStatus":"unaffected","versions":[{"version":"3.5.1","status":"affected","lessThan":"3.34.3","versionType":"semver"}],"collectionURL":"https://repo.hex.pm","cpes":["cpe:2.3:a:ash-project:ash:*:*:*:*:*:*:*:*"],"modules":["'Elixir.Ash.Type.Atom'"],"programFiles":["lib/ash/type/atom.ex"],"programRoutines":[{"name":"'Elixir.Ash.Type.Atom':cast_value/2"}],"repo":"https://github.com/ash-project/ash"},{"vendor":"ash-project","product":"ash","packageName":"ash-project/ash","packageURL":"pkg:github/ash-project/ash","defaultStatus":"unaffected","versions":[{"version":"2970ba3bd5d36d6ad04c731ac87385375d457147","status":"affected","lessThan":"5282f3f513053628cdd1bf2236ea22d975d934d4","versionType":"git"}],"collectionURL":"https://github.com","cpes":["cpe:2.3:a:ash-project:ash:*:*:*:*:*:*:*:*"],"modules":["'Elixir.Ash.Type.Atom'"],"programFiles":["lib/ash/type/atom.ex"],"programRoutines":[{"name":"'Elixir.Ash.Type.Atom':cast_value/2"}],"repo":"https://github.com/ash-project/ash"}],"references":[{"url":"https://cna.erlef.org/cves/CVE-2026-94201.html","name":"EEF CNA record for CVE-2026-94201","tags":["related","third-party-advisory"]},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-94201","name":"OSV record EEF-CVE-2026-94201","tags":["related"]},{"url":"https://github.com/ash-project/ash/commit/2970ba3bd5d36d6ad04c731ac87385375d457147","name":"Introducing commit 2970ba3 in ash-project/ash","tags":["related"]},{"url":"https://github.com/ash-project/ash/commit/5282f3f513053628cdd1bf2236ea22d975d934d4","name":"Fix commit 5282f3f in ash-project/ash","tags":["patch"]}],"metrics":[{"cvssV4_0":{"Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","Safety":"NOT_DEFINED","attackComplexity":"LOW","attackRequirements":"PRESENT","attackVector":"NETWORK","baseScore":8.2,"baseSeverity":"HIGH","privilegesRequired":"NONE","providerUrgency":"NOT_DEFINED","subAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","userInteraction":"NONE","valueDensity":"NOT_DEFINED","vectorString":"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","version":"4.0","vulnAvailabilityImpact":"HIGH","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE","vulnerabilityResponseEffort":"NOT_DEFINED"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-770","description":"CWE-770 Allocation of Resources Without Limits or Throttling","lang":"en","type":"CWE"}]}],"providerMetadata":{"shortName":"EEF","orgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","dateUpdated":"2026-10-05T19:19:51.326Z"},"configurations":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"<p>Reachable only when an application exposes a public, filterable <code>:atom</code> attribute declared with the <code>unsafe_to_atom?: true</code> constraint, and an actor can supply filter values for it (for example through AshGraphql, AshJsonApi, or <code>Ash.Query.filter_input/2</code>). AshPaperTrail's version resources ship such an attribute (<code>version_action_name</code>) by default.</p>"},{"base64":false,"type":"text/markdown","value":"Reachable 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."}],"value":"Reachable 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."}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:a:ash-project:ash:*:*:*:*:*:*:*:*","versionEndExcluding":"3.34.3","versionStartIncluding":"3.5.1","vulnerable":true}],"negate":false,"operator":"OR"}],"operator":"AND"}],"credits":[{"lang":"en","type":"finder","value":"Quinn Wilton"},{"lang":"en","type":"reporter","value":"Quinn Wilton"},{"lang":"en","type":"remediation developer","value":"Zach Daniel / Ash Project"},{"lang":"en","type":"coordinator","value":"Jonatan Männchen / EEF"}],"dateAssigned":"2026-10-04T15:49:18.000Z","impacts":[{"capecId":"CAPEC-130","descriptions":[{"lang":"en","value":"CAPEC-130 Excessive Allocation"}]}],"source":{"discovery":"EXTERNAL"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-10-06T13:41:07.117450Z","id":"CVE-2026-94201","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-06T13:41:22.142Z"}}]}}}