Deserialization of Untrusted Data Affecting apache-airflow-core package, versions [3.0.0,3.4.0)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Start learning- Snyk IDSNYK-PYTHON-APACHEAIRFLOWCORE-22391736
- published10 Nov 2026
- disclosed9 Nov 2026
- creditQi Qin, Hama1cco, Zhixi "Jace" Sun, Michael Lip
Introduced: 9 Nov 2026
NewCVE-2026-111421 (opens in a new tab)How to fix?
Upgrade apache-airflow-core to version 3.4.0 or higher.
Overview
Affected versions of this package are vulnerable to Deserialization of Untrusted Data via the _check_forbidden_xcom_keys validator in the Task Execution API's set_xcom handler, which fails to inspect XCom values submitted as JSON string literals. The _walk helper recursively checks dict and list structures for reserved serialization keys (__classname__, __type, __var, etc.) but does not attempt to parse string values, so a DAG author's task can write an XCom whose value is a JSON-encoded string containing those reserved keys. When a user later retrieves that XCom through the API with ?deserialize=true, the API server re-parses the string into a dict and instantiates classes from the airflow.* namespace with attacker-controlled arguments. This is an incomplete fix for CVE-2026-59242.
Details
Serialization is a process of converting an object into a sequence of bytes which can be persisted to a disk or database or can be sent through streams. The reverse process of creating object from sequence of bytes is called deserialization. Serialization is commonly used for communication (sharing objects between multiple hosts) and persistence (store the object state in a file or a database). It is an integral part of popular protocols like Remote Method Invocation (RMI), Java Management Extension (JMX), Java Messaging System (JMS), Action Message Format (AMF), Java Server Faces (JSF) ViewState, etc.
Deserialization of untrusted data (CWE-502) is when the application deserializes untrusted data without sufficiently verifying that the resulting data will be valid, thus allowing the attacker to control the state or the flow of the execution.