Apache Airflow XCom API permits unsafe deserialization through JSON string literals

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

5.4 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

EPSS

• CVE-2026-59242: 0.53% estimated exploitation activity in the next 30 days; percentile 44.80 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Apache Airflow's XCom GET /api/v2/{...}/xcomEntries/{key}?deserialize=true endpoint passed a string-literal payload through BaseXCom.deserializevalue without the checkforbiddenxcomkeys 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.

Published by the source

12 Aug 2026, 18:31 UTC

Last modified by the source

2 Oct 2026, 23:12 UTC

Source last checked

26 Oct 2026, 13:54 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-fcmm-42r9-mmmm

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# Patch Next advisory brief: CVE-2026-59242

Advisory: Apache Airflow XCom API permits unsafe deserialization through JSON string literals
IDs: CVE-2026-59242, GHSA-fcmm-42r9-mmmm
Record: https://patchnext.com/advisories/cve-2026-59242 (revision 1, source checked 26 Oct 2026, 13:54 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.4)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: apache-airflow 3.3.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI apache-airflow: affected < 3.3.1; fixed in 3.3.1

## Suggested inspection (read-only)
- `python -m pip show apache-airflow`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on apache-airflow.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-fcmm-42r9-mmmm (GitHub-reviewed advisory GHSA-fcmm-42r9-mmmm lists affected ranges: PyPI apache-airflow >=0 <3.3.1)

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