CVE-2026-82734 in ash
Summary
by MITRE • 09/01/2026
Improper Validation of Specified Quantity in Input vulnerability in ash-project ash allows an attacker to submit a non-finite decimal value that bypasses numeric bounds constraints or fails later operations on the value.
Ash.Type.Decimal cast input through Ecto's decimal cast in cast_input/2 and cast_stored/2 (lib/ash/type/decimal.ex) without checking that the resulting value is finite. Elixir's Decimal represents Infinity and NaN as valid structs, so a value such as "Infinity" or "NaN" passed casting and was persisted. Because NaN compares as false against every bound, min and max constraints do not reject it, and the stored special value later raises when used in Decimal arithmetic or is refused by the data layer, failing subsequent requests. The fix rejects any non-finite Decimal during casting.
This issue affects ash: from 1.28.0 before 3.32.2.
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Analysis
by VulDB Data Team • 09/01/2026
The vulnerability identified as Improper Validation of Specified Quantity in Input within the Ash framework represents a critical flaw in how numeric data is processed and persisted, specifically affecting versions ranging from 1.28.0 up to but not including 3.32.2. This security issue stems from an insufficient validation mechanism when handling decimal inputs through Ecto's casting functions, namely cast_input/2 and cast_stored/2 located in the lib/ash/type/decimal.ex module. The core technical flaw lies in the failure of these functions to verify that the resulting Decimal struct is finite before allowing it to be persisted or used within application logic. In the Elixir ecosystem, the Decimal library explicitly supports special values such as Infinity and Not a Number (NaN) as valid structs. Consequently, when an attacker submits input strings representing these non-finite states, the casting process accepts them without raising errors during the initial validation phase. This behavior creates a significant gap in data integrity controls, allowing malicious or malformed data to bypass standard numeric bounds constraints that rely on comparative operators like less than or greater than checks against minimum and maximum limits.
From an operational perspective, this vulnerability leads to inconsistent application states and potential service disruptions. Because NaN values compare as false against every bound check, including min and max constraint validations, they slip through the initial filtering layers undetected. Once persisted into the database, these non-finite decimal values cause subsequent failures when the application attempts to perform arithmetic operations on them or when the underlying data layer rejects the invalid storage format. This results in runtime exceptions that can crash individual requests or degrade system stability if not properly handled by error catching mechanisms elsewhere in the codebase. The impact extends beyond simple errors, as it may lead to incorrect calculations in financial or analytical contexts where precise numeric precision is mandatory, potentially causing data corruption or misleading outputs depending on how downstream processes interpret these invalid states.
This vulnerability aligns with CWE-20 Improper Input Validation and CWE-754: Improper Check for Unusual or Exceptional Conditions from the Common Weakness Enumeration standards. It also maps to ATT&CK technique T1190: Exploit Public-Facing Application, as it involves exploiting a flaw in how an application processes input data that is potentially exposed through API endpoints or user interfaces. The lack of rigorous type checking for edge cases like non-finite numbers allows attackers to inject anomalous data that disrupts normal program flow. To mitigate this risk, developers must ensure that all decimal inputs are validated not only for their numeric range but also for their finiteness before persistence. This involves explicitly checking the Decimal struct's properties or using library functions that reject NaN and Infinity values during the casting phase. Upgrading to Ash version 3.32.2 or later resolves this issue by implementing strict validation logic that rejects any non-finite Decimal structures immediately upon input, thereby preventing these invalid states from entering the application's data layer and ensuring robust handling of numeric inputs in accordance with secure coding best practices.