CVE-2026-42359

Home/CVE/A bug in Apache Airflow's XCom PATCH endpoint `PATCH /api/v2/xcomEntries/{key}` allowed an authenticated UI/API user wit

CVE

A bug in Apache Airflow's XCom PATCH endpoint `PATCH /api/v2/xcomEntries/{key}` allowed an authenticated UI/API user wit

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.

HIGH · CVSS 8.8 EPSS 0.0007

Schedule remediation

CVSS base score ≥ 7.0

Sigma rules0 YARA rules0

Look this up elsewhere - one-click external pivots

NVD CVE.org CISA Vulners Exploit-DB GitHub PoC VulnCheck KEV GreyNoise

▸ How to read a CVE - triage first, then detect and patch

This page is every public fact about CVE-2026-42359, cross-linked. Its job is to answer one question fast - does this need my attention now? - and then hand you the two things you do about it. Here is how an analyst reads it.

Triage: should I act now? Four signals, and they are not interchangeable:

CVSSseverity - how bad it is IF exploited, 0-10. A high CVSS alone is not urgency; a flaw can be a perfect 10 and never actually be attacked. EPSSprobability - a model’s estimate of the chance it is exploited in the next 30 days, 0-1. This is the “will it actually happen” signal. CISA KEVconfirmed - it is being exploited in the wild right now. The strongest signal on the page; KEV beats any score. Weaponisedavailability - public exploits / PoCs, and especially Metasploit modules rated Excellent / Great. Reliable, packaged exploit code means low-skill attackers can use it today.

How they combine: KEV, or a dependable Metasploit module, means patch now regardless of CVSS. High CVSS + low EPSS + no exploit is real but not an emergency - schedule it. Low CVSS but KEV-listed still gets patched now. The verdict above already weighed these for you; this is how it got there.

Then what - two workflows:

Detectwhen you cannot patch today, follow this CVE to the ATT&CK techniques it enables, then Build a SIEM detection (the green button) - author a rule, test it in Atomic, deploy it. That buys visibility while the patch waits. PatchAffected products / packages tell you if you are exposed; Fixed versions by distribution and Vendor advisories give the exact version that closes it.

Reading order for the panels below: verdict + badges, then Public exploits / Metasploit (is it weaponised), then ATT&CK techniques + Sigma / IDS rules (can I detect it), then Affected products / packages + Fixed versions (am I exposed, what patches it), then Threat actors / IOCs (who uses it), then Scoring & timeline / references (the evidence).

View attack path from CVE-2026-42359

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ATT&CK techniques

Techniques this CVE enables - linked via CWECAPECATT&CK. High◆ = named directly in ATT&CK or Nuclei templates.

T1078 · Valid Accounts

▤ Build a SIEM detection for these techniques

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CAPEC attack patterns

Attack patterns this CVE enables - the bridge from weakness to ATT&CK technique.

CAPEC-CAPEC-586 · Object Injection

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Weakness Classification

CWE-502Deserialization of Untrusted Data

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Affected Products & Versions

apache airflow>= 3.2.0 and < 3.2.2

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Affected Packages

Language-ecosystem packages (from OSV) tied to this CVE, with the version that fixes it - the dependency-level detail NVD doesn’t carry.

PyPI apache-airflow fixed in 3.2.2

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Scoring & Timeline

8.8

HIGH · CVSS v3.1 · [email protected]

View on NVD

Attack Vector

Network Adjacent Local Physical

Attack Complexity

Low High

Privileges Required

None Low High

User Interaction

None Required

Scope

Unchanged Changed

Confidentiality

None Low High

Integrity

None Low High

Availability

None Low High

Published to NVD01 Jun 2026 · 09:16 AM

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

SSVC triage · cisa-vulnrichment

Exploitation

none

Automatable

Technical impact

total

SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.

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References & Sources

Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.

https://github.com/apache/airflow/pull/65915Issue TrackingPatch

https://lists.apache.org/thread/g8dqykpf1p90tysq8tln4qtkqwb1038sMailing ListVendor Advisory

https://www.cve.org/CVERecord?id=CVE-2026-33858Third Party Advisory