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CVE-2026-94201— Filtering an :atom attribute with unsafe_to_atom? can exhaust the BEAM atom table in Ash

Quick assessment

Affected
ash-project ash
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Ash 将 类型的属性存储为字符串，并以字符串形式进行比较。当此类属性在过滤器中被引用时，比较值会通过 进行强制类型转换（coercion）。由于该类型未定义 回调，强制类型转换回退到了默认行为（即 ），而在属性配置了 约束时， 会调用 。 因此，如果攻击者使用可控字符串对这类属性进行过滤，则每提供一个不同的值，就会生成一个新的、永久驻留的原子（atom）。在 BEAM（Erlang 虚拟机）中，原子不会被垃圾回收，且原子表存在容量上限。于是，能够向公开的、可过滤的、且配置了 的 类型属性提供过滤值的攻击者，可以耗

CVSS 8.2 · High

Affected Version Matrix 2

VendorProduct Version RangeStatus
ash-project ash 3.5.1< 3.34.3 affected
2970ba3bd5d36d6ad04c731ac87385375d457147< 5282f3f513053628cdd1bf2236ea22d975d934d4 affected
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I. Basic Information for CVE-2026-94201

Vulnerability Information
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Vulnerability Title
Filtering an :atom attribute with unsafe_to_atom? can exhaust the BEAM atom table in Ash
Source: CVE Program / CVE List V5
Vulnerability 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. 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.
Source: CVE Program / CVE List V5
CVSS Information
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: CVE Program / CVE List V5
Vulnerability Type
不加限制或调节的资源分配
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
ash-project ash 3.5.1 ~ 3.34.3 cpe:2.3:a:ash-project:ash:*:*:*:*:*:*:*:*
ash-project ash 2970ba3bd5d36d6ad04c731ac87385375d457147 ~ 5282f3f513053628cdd1bf2236ea22d975d934d4 cpe:2.3:a:ash-project:ash:*:*:*:*:*:*:*:*

II. Public POCs for CVE-2026-94201

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III. Intelligence Information for CVE-2026-94201

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Other References for CVE-2026-94201 (4)

IV. Related Vulnerabilities

Same product: ash
Same vendor: ash-project
Same weakness: CWE-770

V. Comments for CVE-2026-94201

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