Skip to content

Apache Airflow: Unsafe Deserialization via Legacy Serialization Keys (__type/__var) Bypass in XCom API

High severity GitHub Reviewed Published Apr 13, 2026 to the GitHub Advisory Database • Updated Apr 14, 2026

Package

pip apache-airflow (pip)

Affected versions

>= 3.1.8, < 3.2.0

Patched versions

3.2.0

Description

Dag Authors, who normally should not be able to execute code in the webserver context could craft XCom payload causing the webserver to execute arbitrary code. Since Dag Authors are already highly trusted, severity of this issue is Low.

Users are recommended to upgrade to Apache Airflow 3.2.0, which resolves this issue.

References

Published by the National Vulnerability Database Apr 13, 2026
Published to the GitHub Advisory Database Apr 13, 2026
Last updated Apr 14, 2026
Reviewed Apr 14, 2026

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(21st percentile)

Weaknesses

Deserialization of Untrusted Data

The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid. Learn more on MITRE.

CVE ID

CVE-2026-33858

GHSA ID

GHSA-mc4f-r875-v87w

Source code

Loading Checking history
See something to contribute? Suggest improvements for this vulnerability.