What is CVE-2026-66909?

CVE-2026-66909 is a critical-severity vulnerability in Apache Cxf, classified under Deserialization of Untrusted Data. CVSS score: 9.8/10. Published 2026-08-06.

How severe is CVE-2026-66909?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Deserialization in Apache Cxf

CVE-2026-66909

Apache CXF's JMS transport deserializes the body of any inbound JMS ObjectMessage using native Java deserialization, with no type restrictions in place. Any attacker able to place a message on the service's JMS destination can submit a malicious serialized object, leading to denial of service or, if a suitable gadget class is on the classpath, remote code execution. The fix disables ObjectMessage deserialization by default, with a configuration switch to re-enable it if needed. Users are recommended to upgrade to versions 4.2.3 or 4.1.8 or 3.6.12, which fix this issue.

Vulnerability class: Insecure Deserialization

EPSS: 0.007 (50.4th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

Affected products

Apache Cxf
Apache Software Foundation Cxf — versions 4.2.0, 4.0.0, 0

Weakness classification (CWE)

CWE-502 — Deserialization of Untrusted Data

References

security@apache.org (vendor-advisory, Mailing List, Vendor Advisory)
af854a3a-2127-422b-91ae-364da2661108

Frequently asked questions

What is CVE-2026-66909?: CVE-2026-66909 is a critical-severity vulnerability in Apache Cxf, classified under Deserialization of Untrusted Data. CVSS score: 9.8/10. Published 2026-08-06.
How severe is CVE-2026-66909?: Critical severity. CVSS v3 base score is 9.8 out of 10.