CVE-2026-59242 is a medium-severity (CVSS 5.4) Deserialization of Untrusted Data vulnerability in apache-airflow. A fix is available for apache-airflow — see the affected versions and patch details below.
Apache Airflow: Arbitrary airflow.* class instantiation on the API server via the XCom deserialize endpoint
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-59242.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-59242 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 394,803 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
apache-airflowReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
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
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | apache-airflow | all versions | 3.3.1pip install --upgrade 'apache-airflow==3.3.1' |
Affected Products
airflowapacheDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for apache-airflow, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update apache-airflow to 3.3.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-59242 is resolved across your whole dependency graph.
Workarounds
Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade.
Frequently Asked Questions
Is CVE-2026-59242 in your dependencies?
Find it across PyPI, including transitive dependencies.