CVE-2026-59242 Apache Software Foundation CVE debrief

Who should care

Defenders responsible for Apache Airflow deployments should assess exposure and prioritize upgrading to apache-airflow 3.3.1 or later. This involves verifying if the system uses a vulnerable version of Apache Airflow and planning vendor-supported updates or mitigations through normal change control where exposure is confirmed.

Why it matters

CVE-2026-59242 allows an authenticated API user to instantiate arbitrary airflow.* classes on the API server, potentially leading to unauthorized access and data manipulation. Defenders should prioritize verifying exposure and upgrading to apache-airflow 3.3.1 or later.

• Instantiating arbitrary airflow.* classes on the API server
• Potential for unauthorized access and data manipulation

Technical summary

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.

Defensive priority

Defenders should prioritize verifying exposure and upgrading to apache-airflow 3.3.1 or later.

Recommended defensive actions

• Verify if the system uses a vulnerable version of Apache Airflow
• Upgrade to apache-airflow 3.3.1 or later
• Restrict access to the XCom endpoint
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and NVD entry provide details on the vulnerability, CWE-502, in Apache Airflow's XCom endpoint. The vulnerability allows an authenticated API user with XCom write-and-read access to instantiate arbitrary airflow.* classes on the API server. The CVSS score is 5.4 and the severity is MEDIUM. The CVE was published on 2026-08-12T16:17:09.067Z. Users are advised to upgrade to apache-airflow 3.3.1 or later for mitigation.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.