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

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.

Basic information

Type
reviewed
Severity
high
Advisory on GitHub
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Repository advisory
Source code
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Published (advisory)
2026-04-13 15:31:43 UTC
Updated
2026-06-05 14:29:08 UTC
GitHub reviewed
2026-04-14 23:17:35 UTC
NVD published
2026-04-13

EPSS Score

Score Percentile
0.20% 41.91%

CVSS Scores

Base score Version Severity Vector
8.8 3.1
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.

Identifiers

CWEs

CWE id Name
CWE-502 Deserialization of Untrusted Data

Affected packages (1)

Vulnerable version ranges and first patched releases as published by GitHub.

Ecosystem Package Vulnerable range First patched Vulnerable functions
pip apache-airflow >= 3.1.8, < 3.2.0 3.2.0

References

cvelogic Threat Intelligence