CVE-2026-94201 (GCVE-0-2026-94201)
Vulnerability from cvelistv5 – Published: 2026-10-05 19:19 – Updated: 2026-10-06 13:41
VLAI
EPSS
VEX
Title
Filtering an :atom attribute with unsafe_to_atom? can exhaust the BEAM atom table in Ash
Summary
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.
Filtering 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.
The 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.
This issue affects ash: from 3.5.1 before 3.34.3.
Severity
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-10-06 13:41 UTC
CWE
- CWE-770 - Allocation of Resources Without Limits or Throttling
Assigner
References
4 references
| URL | Tags |
|---|---|
| https://cna.erlef.org/cves/CVE-2026-94201.html | relatedthird-party-advisory |
| https://osv.dev/vulnerability/EEF-CVE-2026-94201 | related |
| https://github.com/ash-project/ash/commit/2970ba3… | related |
| https://github.com/ash-project/ash/commit/5282f3f… | patch |
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| ash-project | ash |
Affected:
3.5.1 , < 3.34.3
(semver)
cpe:2.3:a:ash-project:ash:*:*:*:*:*:*:*:* |
||
| ash-project | ash |
Affected:
2970ba3bd5d36d6ad04c731ac87385375d457147 , < 5282f3f513053628cdd1bf2236ea22d975d934d4
(git)
cpe:2.3:a:ash-project:ash:*:*:*:*:*:*:*:* |
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"programRoutines": [
{
"name": "\u0027Elixir.Ash.Type.Atom\u0027:cast_value/2"
}
],
"repo": "https://github.com/ash-project/ash",
"vendor": "ash-project",
"versions": [
{
"lessThan": "3.34.3",
"status": "affected",
"version": "3.5.1",
"versionType": "semver"
}
]
},
{
"collectionURL": "https://github.com",
"cpes": [
"cpe:2.3:a:ash-project:ash:*:*:*:*:*:*:*:*"
],
"defaultStatus": "unaffected",
"modules": [
"\u0027Elixir.Ash.Type.Atom\u0027"
],
"packageName": "ash-project/ash",
"packageURL": "pkg:github/ash-project/ash",
"product": "ash",
"programFiles": [
"lib/ash/type/atom.ex"
],
"programRoutines": [
{
"name": "\u0027Elixir.Ash.Type.Atom\u0027:cast_value/2"
}
],
"repo": "https://github.com/ash-project/ash",
"vendor": "ash-project",
"versions": [
{
"lessThan": "5282f3f513053628cdd1bf2236ea22d975d934d4",
"status": "affected",
"version": "2970ba3bd5d36d6ad04c731ac87385375d457147",
"versionType": "git"
}
]
}
],
"configurations": [
{
"lang": "en",
"supportingMedia": [
{
"base64": false,
"type": "text/html",
"value": "\u003cp\u003eReachable only when an application exposes a public, filterable \u003ccode\u003e:atom\u003c/code\u003e attribute declared with the \u003ccode\u003eunsafe_to_atom?: true\u003c/code\u003e constraint, and an actor can supply filter values for it (for example through AshGraphql, AshJsonApi, or \u003ccode\u003eAsh.Query.filter_input/2\u003c/code\u003e). AshPaperTrail\u0027s version resources ship such an attribute (\u003ccode\u003eversion_action_name\u003c/code\u003e) by default.\u003c/p\u003e"
},
{
"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\u0027s 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\u0027s 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 M\u00e4nnchen / EEF"
}
],
"dateAssigned": "2026-10-04T15:49:18.000Z",
"descriptions": [
{
"lang": "en",
"supportingMedia": [
{
"base64": false,
"type": "text/html",
"value": "\u003cp\u003eAsh stores \u003ccode\u003e:atom\u003c/code\u003e-typed attributes as strings and compares them as strings. When such an attribute is referenced in a filter, the comparison value is coerced through \u003ccode\u003eAsh.Type.Atom\u003c/code\u003e. Because the type defined no \u003ccode\u003ecoerce/2\u003c/code\u003e callback, coercion fell back to the default (\u003ccode\u003ecast_input/2\u003c/code\u003e), which calls \u003ccode\u003eString.to_atom/1\u003c/code\u003e when the attribute is configured with the \u003ccode\u003eunsafe_to_atom?: true\u003c/code\u003e constraint.\u003c/p\u003e\n\u003cp\u003eFiltering 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 \u003ccode\u003e:atom\u003c/code\u003e attribute declared with \u003ccode\u003eunsafe_to_atom?: true\u003c/code\u003e can exhaust the atom table and crash the node (denial of service). AshPaperTrail is a notable example: its version resources expose a public, filterable \u003ccode\u003eversion_action_name\u003c/code\u003e atom attribute with \u003ccode\u003eunsafe_to_atom?: true\u003c/code\u003e by default.\u003c/p\u003e\n\u003cp\u003eThe fix adds a \u003ccode\u003ecoerce/2\u003c/code\u003e to \u003ccode\u003eAsh.Type.Atom\u003c/code\u003e that never interns atoms \u2014 a comparison value is left as a string, since the type is stored and compared as a string. Setting the attribute from action input (\u003ccode\u003ecast_input/2\u003c/code\u003e, which still honors \u003ccode\u003eunsafe_to_atom?\u003c/code\u003e) is unchanged.\u003c/p\u003e\n\u003cp\u003eThis issue affects ash: from 3.5.1 before 3.34.3.\u003c/p\u003e"
},
{
"base64": false,
"type": "text/markdown",
"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 \u2014 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."
}
],
"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 \u2014 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."
}
],
"impacts": [
{
"capecId": "CAPEC-130",
"descriptions": [
{
"lang": "en",
"value": "CAPEC-130 Excessive Allocation"
}
]
}
],
"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": {
"dateUpdated": "2026-10-05T19:19:51.326Z",
"orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"shortName": "EEF"
},
"references": [
{
"name": "EEF CNA record for CVE-2026-94201",
"tags": [
"related",
"third-party-advisory"
],
"url": "https://cna.erlef.org/cves/CVE-2026-94201.html"
},
{
"name": "OSV record EEF-CVE-2026-94201",
"tags": [
"related"
],
"url": "https://osv.dev/vulnerability/EEF-CVE-2026-94201"
},
{
"name": "Introducing commit 2970ba3 in ash-project/ash",
"tags": [
"related"
],
"url": "https://github.com/ash-project/ash/commit/2970ba3bd5d36d6ad04c731ac87385375d457147"
},
{
"name": "Fix commit 5282f3f in ash-project/ash",
"tags": [
"patch"
],
"url": "https://github.com/ash-project/ash/commit/5282f3f513053628cdd1bf2236ea22d975d934d4"
}
],
"source": {
"discovery": "EXTERNAL"
},
"title": "Filtering an :atom attribute with unsafe_to_atom? can exhaust the BEAM atom table in Ash"
}
},
"cveMetadata": {
"assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"assignerShortName": "EEF",
"cveId": "CVE-2026-94201",
"datePublished": "2026-10-05T19:19:51.326Z",
"dateReserved": "2026-09-24T09:15:02.216Z",
"dateUpdated": "2026-10-05T19:19:51.326Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
}
}
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Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.
Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Vulnerability timeline
Sightings and recorded dates, grouped by day · UTC
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.