Unsafe deserialization in Apache Airflow XCom API via legacy serialization keys
CVE-2026-33858 is an unsafe deserialization vulnerability in Apache Airflow affecting versions 3.1.8 before 3.2.0. The issue is in the XCom API and involves a bypass using legacy serialization keys such as __type and __var. A DAG author can craft a malicious XCom payload that is processed in a way that causes arbitrary code execution in the Airflow webserver context. Apache notes that DAG authors normally should not be able to execute code in the webserver context, but this flaw breaks that boundary.
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Impact, mitigation & remediation
What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.
Impact
What an attacker gets, and what they’ve been doing with it.
Mitigation
If you can’t patch tonight, do this now.
Remediation
Patch, then assume compromise.
Exploits
No public exploits tracked yet. Mallory keeps watching.
No public exploit code observed for this vulnerability.
Affected products & vendors
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
Recent activity
9 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
An earlier Apache Airflow vulnerability involving XCom reserved-key validation on the POST/set path, referenced here because CVE-2026-42359 bypasses its fix via the PATCH path.
An arbitrary code execution vulnerability in Apache Airflow where DAG Authors can craft an XCom payload that causes the webserver to execute arbitrary code.
The version that knows your environment.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.