Vulnerability · Published Aug 12, 2026 · Assigned by apache
CVE-2026-59242Apache Airflow: Arbitrary airflow.* class instantiation on the API server via the XCom deserialize endpoint
Medium 5.4
In plain English
A medium-severity unsafe deserialization in Apache Airflow from Apache Software Foundation. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 45% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Apache Airflow's XCom `GET /api/v2/{...}/xcomEntries/{key}?deserialize=true` endpoint passed a string-literal payload through `BaseXCom.deserialize_value` without the `_check_forbidden_xcom_keys` guard, allowing an authenticated API user with XCom write-and-read access to instantiate arbitrary `airflow.*` classes on the API server (CWE-502). An authenticated user who can write an XCom value and then read it back with `deserialize=true` triggers the unsafe instantiation. Users are advised to upgrade to apache-airflow 3.3.1 or later, which rejects reserved XCom serialization keys submitted as JSON string literals.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| PyPI | apache-airflow | 3.3.1 | GHSA-fcmm-42r9-mmmm |
| PyPI | apache-airflow | 3.3.1 | PYSEC-2026-3992 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Apache Software Foundation | Apache Airflow | 0 – before 3.0.0 |
| Apache Software Foundation | Apache Airflow | 3.0.0 – before 3.3.1 |
Weakness: CWE-502 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N