Vulnerability · high
Apache Airflow scheduler deserializes task-controlled XCom values (CVE-2026-86829)
Tier C · Keep an eye on it – Check if you’re affected
Who’s exposed: Airflow deployments running scheduler versions before 3.4.0
Tier C because: Hits tech teams
Reach
Attack
Damage
Fix
Popular tool
What to do
- Upgrade Apache Airflow to 3.4.0 or later
The Brief
- Apache Airflow's scheduler fully deserializes XCom values written by task code while evaluating task dependencies.
- A Dag author who controls what a task writes can exploit this, per the advisory's description.
- Affected versions are Apache Airflow before 3.4.0; the advisory is tracked as CVE-2026-86829 and rated important.
Why it matters
Deployments running affected Airflow versions may let Dag authors trigger unsafe deserialization inside the scheduler, so upgrading removes this exposure.
The checklist behind the tier
Checklist · 2 of 10 yes
| Yes | Hits tech teams | Judgment: Apache Airflow is orchestration software that data and dev teams build with and run. |
| No | Core infrastructure | Judgment: Airflow is a popular tool, not foundational software like OpenSSH or the Linux kernel. |
| Yes | Popular tool | Judgment: Apache Airflow is a widely used workflow orchestration platform across many teams. |
| No | Exploited in the wild | Open Source Security: the advisory describes the flaw only; no observed attacks are reported. |
| No | Public exploit | Open Source Security: the advisory gives a description and no exploit code or PoC is mentioned. |
| No | Remote, no login | Open Source Security: exploitation requires a Dag author who controls what a task writes, so credentials are needed. |
| No | Full takeover | Open Source Security: the source describes unsafe deserialization but does not state code execution or admin takeover. |
| No | Secrets exposed | Open Source Security: no data theft or exposure of secrets or customer data is reported. |
| No | Supply chain | Open Source Security: a bug in the scheduler's deserialization; no compromised package or build is reported. |
| No | No fix yet | Open Source Security: affected versions are before 3.4.0, implying a fixed release exists. |
The official record
From CVE.org, CISA’s Known Exploited Vulnerabilities catalog, FIRST EPSS and the GitHub Advisory Database. Where these answer a checklist fact, they win over the reporting.
- Exploited
- Not in CISA’s exploited catalog
Timeline
Vulnerability posted to oss-sec by Rahul Vats
Open Source Security
CVE-2026-86829: Apache Airflow: Deserialization of task-controlled XCom values in the Scheduler during dependency evaluation
Source
CVE-2026-86829: Apache Airflow: Deserialization of task-controlled XCom values in the Scheduler during dependency evaluation ↗ Open Source Security · 3h ago
First seen · 1 source · Full story page · How tiers are decided