`CVE-2026-66909` Apache CXF

Affected software	Apache CXF
Severity	9.8 Critical CVSS 3.1
Weakness	Deserialization of untrusted data (CWE-502)
Published	6 Aug 2026
Updated	24 Oct 2026

Description

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.

Exploitation status

No public exploit

No exploit has been reported in the sources we check.

CISA KEV not listed
VulnCheck KEV not listed
CISA Vulnrichment exploitation: none
Indexed PoC none indexed
EPSS 0.69% chance in 30 days

Waratek protection

Protected by Waratek

Waratek has a rule that blocks attacks on this vulnerability.

Protection full Deserialization, Process
Action available security rule
Review automated Inferred
Record active

Decided by	A vulnerability class already blocked by an ARMR security rule
Finding	Protected by Waratek's ARMR deserialization security rule, which blocks this class of attack at the JVM level without a rule written for this CVE specifically. The CVE's weakness is CWE-502: Deserialization of Untrusted Data.

Decided by

A vulnerability class already blocked by an ARMR security rule

Finding

Protected by Waratek's ARMR deserialization security rule, which blocks this class of attack at the JVM level without a rule written for this CVE specifically. The CVE's weakness is CWE-502: Deserialization of Untrusted Data.

How to mitigate CVE-2026-66909

Apply the vendor's fix for Apache CXF. Until you can, Waratek RASP blocks exploitation with its deserialization and process rules. It runs inside the Java application, with no code changes.

Waratek RASP Runtime protection for Java applications

Affected software and releases

Products and versions

1 product, 3 version entries

Source	Vendor	Product	Scheme	Affected versions
nvd	apache	cxf	generic	＜ 3.6.12 · ≥ 4.0.0 and ＜ 4.1.8 · ≥ 4.2.0 and ＜ 4.2.3

Source

Vendor

Product

Scheme

Affected versions

nvd

apache

cxf

generic

＜ 3.6.12 · ≥ 4.0.0 and ＜ 4.1.8 · ≥ 4.2.0 and ＜ 4.2.3

References

URL	Tags
https://lists.apache.org/thread/lr5d4tg6tf7j29jmw8wt242oowonjqpx	Mailing List, Vendor Advisory
http://www.openwall.com/lists/oss-security/2026/08/06/18

URL

Timeline

Published	2026-08-06	By the CVE Program.
NVD record modified	2026-10-24	NVD's own last-modified date for this record.

Published

2026-08-06

By the CVE Program.

NVD record modified

2026-10-24

NVD's own last-modified date for this record.

How VRT decided (18 of 24 rules ran)

18 of 24 rules ran. The rest didn't run because an earlier rule had already settled the CVE.

# Rule Outcome Status Detail

identity: Does this identifier describe a vulnerability at all? the first rule that matches decides

1 rejected no match CVE Program withdrawal of this identifier

scope: Is it a vulnerability Waratek protects? the first rule that matches decides

2 armr-patch-file no match An ARMR patch file on disk for this CVE

3 armr-secure-rule-file no match An ARMR security-rule template on disk for this CVE

4 manual-classification no match A researcher's recorded decision for this specific CVE

5 manual classification no match Manual classification of this CVE in the legacy dataset

6 non-java-upstream no match A root cause in non-Java code: an OS kernel, a C library, or a bundled runtime

7 oracle-component no match The defect being in a component of a tracked product the agent does not reach: JavaFX, the Java SE installer, the JInitiator browser plug-in, the native WebLogic proxy plug-in, or a native part of Oracle Application Server or Collaboration Suite (HTTP Server, Web Cache, Internet Directory, mail and calendar servers). Oracle gives these no CPE of their own and names them only in the description.

8 java-client-side no match Oracle's own risk-matrix note saying the CVE is reached only through untrusted code in the Java sandbox (applets, Web Start) or only through a client installation of Java, so a server running its own trusted code is not exposed

9 osv-maven no match An OSV.dev record of this CVE affecting a package published to Maven Central. When every such package is one business applications do not use (Minecraft mods and launchers, Fastjson) and no tracked product is named by CPE, it settles the CVE as Outside Waratek scope instead

10 cna-maven-package matched In scope CNA declares the affected component is a Maven artifact

11 known-cpe-product not reached An NVD CPE naming a product ARMR tracks

12 cna-cpe-product not reached A CPE the CNA published naming a tracked product. Oracle publishes these on advisory day, months before NVD.

13 oracle-advisory-family not reached A tracked product family named in Oracle's own risk matrix. CPE cannot carry a suite name, only a module.

14 cna-named-product not reached A tracked product named in words by the CVE's own CNA, on a record with no CPE yet. Apache and Eclipse publish these on advisory day, before NVD adds CPE data.

15 non-deployable-product not reached The only affected product being a sealed appliance image, where Java runs but no -javaagent can be attached

16 unmatched-product not reached No tracked product matched above, and none present at all

disposition: What do we do about one that is? every rule runs

17 patch-hint no match A reference pointing at the upstream fix: a commit, a PR, a Red Hat bug

18 open-source-maven no match The affected package being open source on Maven, so the fix can be read

19 poc-derivable no match An indexed exploit clearing the evidence bar to reverse-engineer, where there is no source to read

20 no-exploit matched No exploit published No public exploits or POCs found in Exploit-DB, Nuclei templates, Metasploit modules, or GitHub POC repositories, and CISA's Vulnrichment assessment records no demonstrated exploit. No upstream fix reference or open-source Maven package was found either, so there is nothing to act on from either direction.

21 secure-rule-match decided it matched Protected by Waratek CWE-502 (Deserialization of Untrusted Data) is mitigable by an ARMR deserialization security rule.

22 exploited-no-fix-or-poc skipped Somebody exploiting this CVE (a CISA or VulnCheck KEV listing, or a CISA verdict of active exploitation), with no fix, source code or PoC to build a rule from

23 below-action-threshold skipped Medium or Low severity, no CISA or VulnCheck KEV listing, no PoC clearing the evidence bar, no CISA verdict, no Oracle advisory

24 no-exploit-published skipped Exploit code for this candidate, published in a reviewed catalogue or a GitHub repository with 5 or more stars, or in use per CISA or VulnCheck; not only a CISA verdict, a forecast, or nothing at all

Products the scope rules checked

The products this CVE's record names, and whether VRT tracks each one. The scope rules decided on these.

Vendor Product Tracked CPE Source

apache cxf tracked cpe:2.3:a:apache:cxf:*:*:*:*:*:*:*:* yaml

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