Apache Airflow: Execution API: set_xcom skips the reserved-key check, so task-written XComs instantiate airflow. classes on the API server
- Exploited
- No known exploitation
- Fix
- Fixed in 3.4.0
- Who is exposed
- Not reported
Do first: Upgrade to a fixed version: 3.4.0.
- Last modified
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 25/100 · provisional
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: no
- Technical impact: total
Summary
Apache Airflow's Task Execution API stores task-written XComs without the reserved-key check, so a Dag author's task can write an XCom that, when a user views it through the API with deserialization enabled, makes the API server instantiate `airflow.*` classes with arguments the Dag author chose. This route remains open even after the earlier fix for CVE-2026-59242.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
Read the original description
Apache Airflow's Task Execution API stored XCom values written by a task without the reserved-key check applied elsewhere, so a Dag author's task could write an XCom that, when a user later viewed it through the API with deserialization enabled, made the API server instantiate classes from the airflow.* namespace with arguments the Dag author chose. This is an incomplete fix for CVE-2026-59242: users who applied that fix in apache-airflow 3.3.1 remain affected through this route and should upgrade to apache-airflow 3.4.0 or later.
cve.now Index
- Exploitation0/40No signal
- Exposure3/25Reachable over the network · Unknown: No advisory context yet
- Reach12/20apache-airflow-core: 647K downloads a week
- Severity9.8/10CVSS 8.8, total technical impact per CISA
- No patch0/5No signal
What would change the score
- Would score about 80 if added to CISA KEV
- Would score about 75 if CISA's SSVC rates exploitation active
- Would score about 44 if advisories confirm default setups are exposed
Impact
- Widely used
apache-airflow-core has 647k weekly downloads.Source: pypistats.org
473 packages depend on apache-airflow-core.Source: deps.dev
What to do
Upgrade to a fixed version: 3.4.0.
Timeline
- CVE published
- First seen by cve.now
- CISA SSVC assessment
Exploitation: none · Automatable: no · Technical impact: total
- Record last updated
Affected versions
From 3.0.0 · fixed in 3.4.0
Fixed in 3.4.0 (released Nov 6, 2026, 3 days before disclosure).
The latest release, 3.4.0, is not affected.
Evidence 4
- Advisory
- Patch
- Patch
- Link
Corrections
None so far.
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Questions about CVE-2026-111421
Is CVE-2026-111421 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
Which versions are affected by CVE-2026-111421?
apache-airflow-core (PyPI): from 3.0.0 before 3.4.0.Source: cve.now feed data
How do I fix CVE-2026-111421?
Upgrade to a fixed version: 3.4.0.Source: cve.now feed data