Apache Airflow: Arbitrary airflow.* class instantiation on the API server via the XCom deserialize endpoint (CVE-2026-59242) | HOL Guard CVE

Medium · CVSS 5.4CVE-2026-59242

Apache Airflow: Arbitrary airflow.* class instantiation on the API server via the XCom deserialize endpoint

Answer in brief

CVE-2026-59242 records a Medium severity (CVSS 5.4) vulnerability in Apache Airflow: Arbitrary airflow.* class instantiation on the API server via the XCom deserialize endpoint. The current sources do not mark it as known exploited. The current feed maps Apache Software Foundation/Apache Airflow (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Aug 12, 2026Updated Sep 16, 2026Source checked Sep 26, 2026First seen by HOL Aug 12, 2026Material review Sep 16, 2026

Upstream Advisory

Key facts

Risk: Medium · CVSS 5.4
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

CVSS is 5.4. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Apache Software Foundation/Apache Airflow (generic). Check affected ranges and fixed versions before updating.

Affected products and reported versions
Product	Affected versions	Fixed versions
cpe:2.3:a:apache:airflow::::::::	Not reported	Not reported

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Apache Software Foundation/Apache Airflowgeneric	>=0 <3.3.1	3.3.1

Recommended response

Check inventory. Check lockfiles and deployed manifests for Apache Software Foundation/Apache Airflow.
Review the reported fix. Update Apache Software Foundation/Apache Airflow to 3.3.1 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Aug 12, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 16, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 12, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.