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Vulnerability details: VCID-y78u-y824-afc4
Vulnerability ID VCID-y78u-y824-afc4
Aliases BIT-airflow-2026-42359
CVE-2026-42359
PYSEC-2026-185
Summary 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.
Status Published
Exploitability 0.5
Weighted Severity 7.9
Risk 4.0
Affected and Fixed Packages Package Details
Weaknesses (1)
CWE-502 Deserialization of Untrusted Data
System Score Found at
epss 0.0007 https://api.first.org/data/v1/epss?cve=CVE-2026-42359
epss 0.0007 https://api.first.org/data/v1/epss?cve=CVE-2026-42359
epss 0.0007 https://api.first.org/data/v1/epss?cve=CVE-2026-42359
cvssv3.1 8.8 https://github.com/apache/airflow/pull/65915
ssvc Track https://github.com/apache/airflow/pull/65915
cvssv3.1 8.8 https://lists.apache.org/thread/g8dqykpf1p90tysq8tln4qtkqwb1038s
ssvc Track https://lists.apache.org/thread/g8dqykpf1p90tysq8tln4qtkqwb1038s
cvssv3.1 8.8 https://www.cve.org/CVERecord?id=CVE-2026-33858
ssvc Track https://www.cve.org/CVERecord?id=CVE-2026-33858
Reference id Reference type URL
https://api.first.org/data/v1/epss?cve=CVE-2026-42359
65915 https://github.com/apache/airflow/pull/65915
CVERecord?id=CVE-2026-33858 https://www.cve.org/CVERecord?id=CVE-2026-33858
g8dqykpf1p90tysq8tln4qtkqwb1038s https://lists.apache.org/thread/g8dqykpf1p90tysq8tln4qtkqwb1038s
No exploits are available.
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Found at https://github.com/apache/airflow/pull/65915
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: SSVCv2/E:N/A:N/T:T/P:M/B:A/M:M/D:T/2026-06-02T03:55:43Z/ Found at https://github.com/apache/airflow/pull/65915
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Found at https://lists.apache.org/thread/g8dqykpf1p90tysq8tln4qtkqwb1038s
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: SSVCv2/E:N/A:N/T:T/P:M/B:A/M:M/D:T/2026-06-02T03:55:43Z/ Found at https://lists.apache.org/thread/g8dqykpf1p90tysq8tln4qtkqwb1038s
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Found at https://www.cve.org/CVERecord?id=CVE-2026-33858
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: SSVCv2/E:N/A:N/T:T/P:M/B:A/M:M/D:T/2026-06-02T03:55:43Z/ Found at https://www.cve.org/CVERecord?id=CVE-2026-33858
Exploit Prediction Scoring System (EPSS)
Percentile 0.21503
EPSS Score 0.0007
Published At June 11, 2026, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2026-06-11T16:44:27.061705+00:00 Vulnrichment Import https://github.com/cisagov/vulnrichment/blob/develop/2026/42xxx/CVE-2026-42359.json 38.6.0