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Response snapshot Nov 3, 2026, 08:21 UTC

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VulnerabilityCVE-2026-42359

A bug in Apache Airflow's XCom PATCH endpoint `PATCH /api/v2/xcomEntries/{key}` allowed an authenticated UI/API user with XCom write permission on a Dag to set XCom entries under...

A bug in Apache Airflow's XCom PATCH endpoint PATCH /api/v2/xcomEntries/{key} allowed an authenticated UI/API user with XCom write permission on a Dag to set XCom entries under reserved key names (e.g. return_value) that the matching POST endpoint already validated against FORBIDDEN_XCOM_KEYS.

At a glance

Exploited
Not known
Severity
8.8 High (CVSS 3.1)
Chance of exploitation
Not estimated
Sources
2 independent sources

What to do

Check the vendor advisory for affected versions and fixes.

Read NVD CVE-2026-42359 (opens a new tab)

What happened

A bug in Apache Airflow's XCom PATCH endpoint PATCH /api/v2/xcomEntries/{key} allowed an authenticated UI/API user with XCom write permission on a Dag to set XCom entries under reserved key names (e.g. return_value) that the matching POST endpoint already validated against FORBIDDEN_XCOM_KEYS.

The endpoint also accepted serialized payload shapes the triggerer's deserializer treats as code; combined, this allowed RCE on the triggerer when the affected task next deferred. Affects deployments where untrusted users have XCom write permission on Dags that defer to the triggerer.

This is a fix-bypass of CVE-2026-33858: PR #64148 added the FORBIDDEN_XCOM_KEYS validator only on the POST/set path; the PATCH path was not covered. Users who already upgraded for CVE-2026-33858 should additionally upgrade to apache-airflow 3.2.2 or later to cover the PATCH-path bypass.

Scores and how they were measured

CVSS base severity

8.8

Version 3.1As of

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

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

Not available

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Related technology

Sources

  1. Primary source

    NVD CVE-2026-42359 (opens a new tab)

    NVD record: description, CVSS (the CNA score is preferred), affected products, and publication date. Not evidence of exploitation.

    Published Checked

  2. Primary source

    Vendor advisory (via NVD references) (opens a new tab)

    The vendor advisory referenced by the CVE record, for affected versions and fixes.

    Published Date not suppliedChecked

  3. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  4. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, November 3). A bug in Apache Airflow's XCom PATCH endpoint `PATCH /api/v2/xcomEntries/{key}` allowed an authenticated UI/API user with XCom write permission on a Dag to set XCom entries under... (CVE-2026-42359). https://kevwire.com/record/CVE-2026-42359

MLA

"A bug in Apache Airflow's XCom PATCH endpoint `PATCH /api/v2/xcomEntries/{key}` allowed an authenticated UI/API user with XCom write permission on a Dag to set XCom entries under... (CVE-2026-42359)." KEVWire, 3 Nov. 2026, kevwire.com/record/CVE-2026-42359.

Chicago

KEVWire. "A bug in Apache Airflow's XCom PATCH endpoint `PATCH /api/v2/xcomEntries/{key}` allowed an authenticated UI/API user with XCom write permission on a Dag to set XCom entries under... (CVE-2026-42359)." Last modified November 3, 2026. https://kevwire.com/record/CVE-2026-42359.

Evidence summary (plain text)

A bug in Apache Airflow's XCom PATCH endpoint `PATCH /api/v2/xcomEntries/{key}` allowed an authenticated UI/API user with XCom write permission on a Dag to set XCom entries under... (Jun 1, 2026).
A bug in Apache Airflow's XCom PATCH endpoint PATCH /api/v2/xcomEntries/{key} allowed an authenticated UI/API user with XCom write permission on a Dag to set XCom entries under reserved key names (e.g. return_value) that the matching POST endpoint already validated against FORBIDDEN_XCOM_KEYS. The endpoint also accepted serialized payload shapes the triggerer's deserializer treats as code; combined, this allowed RCE on the triggerer when the affected task next deferred. Affects deployments where untrusted users have XCom write permission on Dags that defer to the triggerer.
CVSS 8.8 (version 3.1; evidence as of Nov 3, 2026; https://nvd.nist.gov/vuln/detail/CVE-2026-42359).
Sources:
NVD CVE-2026-42359: https://nvd.nist.gov/vuln/detail/CVE-2026-42359
Vendor advisory (via NVD references): https://lists.apache.org/thread/g8dqykpf1p90tysq8tln4qtkqwb1038s
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-11-03T06:25:58.682Z&lastModEndDate=2026-11-03T08:00:56.062Z&resultsPerPage=500&startIndex=0
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-11-03T05:50:56.450Z&lastModEndDate=2026-11-03T07:25:56.283Z&resultsPerPage=500&startIndex=0
Record ID: CVE-2026-42359.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Nov 3, 2026, 08:00 UTC. Ingestion is not an independent editorial investigation.

NVD status: Analyzed. Publication in the NVD is not evidence of exploitation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

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Record details

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