Deserialization in Apache Airflow
CVE-2026-59242
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.
Vulnerability class: Insecure Deserialization
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N.
EPSS exploit prediction
EPSS: 0.008 (54.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 55th percentile — 54.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.006 · newest: 0.008 · change: +0.002
Affected products
- Apache Airflow
- Apache Software Foundation Airflow — versions 0
Weakness classification (CWE)
References
- github.com/apache/airflow/pull/69378 (Patch, patch, Issue Tracking)
- lists.apache.org/thread/dm0520yhh4mn7qknyoh45r2w6c5qg2mg (vendor-advisory, Mailing List, Vendor Advisory)
- af854a3a-2127-422b-91ae-364da2661108 (Mailing List, Third Party Advisory)
Frequently asked questions
- What is CVE-2026-59242?
- CVE-2026-59242 is a medium-severity vulnerability in Apache Airflow, classified under Deserialization of Untrusted Data. CVSS score: 5.4/10. Published 2026-08-12.
- How severe is CVE-2026-59242?
- Medium severity. CVSS v3 base score is 5.4 out of 10.