CVE-2026-33264: Apache Airflow allows code execution through unsafe serialized DAG deserialization

Should you act?

Critical and remotely reachable

No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
• EPSS 1.6%, percentile 76: FIRST’s model estimates a 1.6% chance of exploitation activity in the next 30 days, higher than 76% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
• Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
• Only applies if your dependency tree includes apache-airflow (PyPI) < 3.3.0, fixed in 3.3.0. Check your lockfile, including transitive dependencies.

What it is

A bug in BaseSerialization.deserialize() allowed unrestricted importstring() of attacker-controlled class paths when the Scheduler / API Server loaded a serialized DAG: a DAG author could embed a malicious trigger into a DAG to gain remote code execution on the API Server / Scheduler process, crossing the Airflow security boundary that DAG-author code must never execute in those processes. Users are advised to upgrade to apache-airflow 3.3.0 or later. As a defense-in-depth mitigation, deployments where DAG-author trust is limited can restrict the [core] alloweddeserializationclasses config to a narrow allowlist.

From the GitHub advisory

A bug in BaseSerialization.deserialize() allowed unrestricted importstring() of attacker-controlled class paths when the Scheduler / API Server loaded a serialized DAG: a DAG author could embed a malicious trigger into a DAG to gain remote code execution on the API Server / Scheduler process, crossing the Airflow security boundary that DAG-author code must never execute in those processes. Users are advised to upgrade to apache-airflow 3.3.0 or later. As a defense-in-depth mitigation, deployments where DAG-author trust is limited can restrict the [core] alloweddeserializationclasses config to a narrow allowlist.

Weakness type: CWE-502.

Product: apache-airflow (PyPI) · Assigned by: apache · Published: 2026-07-07

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Privileges required: none (no login)
• User interaction: none
• Scope: unchanged

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation none, automatable yes, technical impact total.
• FIRST EPSS (model of 2026-10-21): 1.65% probability of exploitation activity in the next 30 days; percentile 76.

Timeline

• 2026-07-07 — CVE record published by apache
• 2026-07-07 — GitHub-reviewed advisory GHSA-2943-9672-r45w published (critical)
• 2026-07-08 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vendor and project advisories, patches

1. github.com github.com
2. github.com github.com
3. lists.apache.org lists.apache.org

Vulnerability records

1. GitHub Advisory GHSA-2943-9672-r45w github.com
2. CVE.org record CVE-2026-33264 cve.org
3. NVD entry CVE-2026-33264 nvd.nist.gov

Other references from the CVE record and advisory

1. openwall.com openwall.com
2. github.com github.com
3. github.com github.com
4. github.com github.com

Critical PyPI advisories · Today’s Security Digest