By default, StaxUtils placed no limit on the total number of elements or the total number of characters in an XML document. A very large request could therefore use a lot of memory and CPU during parsing, especially where CXF builds a DOM from the input (for example SAAJ or WS-Security), and could cause a denial of service when no request size limit was configured. Both limits now have defaults: the maximum element count is 100 × maxChildElements (5,000,000 by default), and the maximum document size is 256M characters. Applications that process larger documents can raise the limits with the org.apache.cxf.stax.maxElementCount and org.apache.cxf.stax.maxXMLCharacters properties. Users are recommended to upgrade to versions 4.2.4 or 4.1.9 or 3.6.13, which fix this issue.

In Apache CXF, the Netty-based HTTP client transport (cxf-rt-transports-http-netty-client) did not verify that the hostname in the server’s TLS certificate matched the host being called. This applied over both HTTP/1.1 and HTTP/2, even when disableCNCheck was left at its default value of false. The certificate chain was validated against the configured trust store, but the endpoint’s identity was not. A network attacker able to intercept traffic could present any certificate trusted by the client, such as a publicly issued certificate for a domain they control, and impersonate the target service. They could then read or modify the exchanged messages, including credentials.  Users are recommended to upgrade to versions 4.2.4 or 4.1.9 or 3.6.13, which fix this issue.

In Apache CXF, the parser for multipart/MTOM attachment part headers did not fully enforce the configured attachment-max-header-size (default 300 characters) and attachment-headers-max-count (default 500) limits. The size limit was applied only to each physical line, not to a header value built from continuation lines or to the combined values of a repeated header. The count limit was checked against the number of distinct header names, not the total number of header lines. A remote, unauthenticated attacker could send a multipart request with very large folded or repeated part headers. The server would then allocate memory without bound, causing a denial of service.  Users are recommended to upgrade to versions 4.2.4 or 4.1.9 or 3.6.13, which fix this issue.

Improper Verification of Cryptographic Signature vulnerability in Apache CXF's JAX-RS XML Security module. The JAX-RS XML Signature interceptors (XmlSigInHandler, XmlSigInInterceptor and the streaming XmlSecInInterceptor) did not ensure that the XML passed to the application was covered by the signature. An attacker with any document signed by a trusted key could wrap it in unsigned content, which the application would then treat as signed. Users are recommended to upgrade to versions 4.2.4 or 4.1.9 or 3.6.13, which fix this issue.

In Apache CXF, STSTokenValidator checks whether a SAML assertion is signed by a trusted certificate before deciding to send it to the STS. That result was stored in one object shared by all requests, so one request could read another's result. A remote, unauthenticated attacker could send a forged assertion signed with an untrusted certificate while legitimate requests were being processed, and it could be accepted as trusted without ever reaching the STS. Only services that use STSTokenValidator to validate SAML tokens without alwaysValidateToSts set are affected.  Users are recommended to upgrade to versions 4.2.4 or 4.1.9 or 3.6.13, which fix this issue.

Apache CXF's STSTokenValidator and Security Token Service (STS) cached validated security tokens under a non-cryptographic 32-bit hash of the token (Java Arrays.hashCode/hashCode()), and treated a cache hit as proof that the presented token had already been validated. An attacker could craft a token (for example a UsernameToken or a self-signed SAML Assertion) whose hash collides with a cached entry. The token would then be accepted without password validation, signature trust verification or a call to the STS. This could let the attacker authenticate as another user and, through STS token validation or renewal, obtain STS-signed tokens for that identity. Users are recommended to upgrade to versions 4.2.4 or 4.1.9 or 3.6.13, which fix this issue.

Apache CXF's FIQL query parser has a vulnerability in how it searches for operators in query expressions. The search pattern can get stuck trying many combinations when it encounters a long string without an operator, causing the parser to consume excessive CPU time. An attacker can send a crafted query to make the server use up CPU resources, potentially slowing down or stopping other requests. The fix was to limit FIQL expressions to 4 KiB by default, preventing attackers from sending extremely long inputs while still allowing normal queries.

Users are recommended to upgrade to versions 4.2.4 or 4.1.9 or 3.6.13, which fix this issue.

Apache CXF’s OIDC relying-party component could redirect users to an attacker-controlled URL after successful authentication. The issue occurs because attacker-controlled state parameters are preserved and later used as redirect targets without validating that the final decoded URI belongs to the RP’s origin. Both directly encoded and double-encoded external URLs can trigger the issue, depending on which validation path is used. Users are recommended to upgrade to versions 4.2.4 or 4.1.9 or 3.6.13, which fix this issue.

CompressionUtils.inflate() decompressed attacker-controlled DEFLATE data with no output-size cap. A small (~KB) crafted payload could expand to gigabytes on the heap. Reachable via JWE decryption when zip=DEF (e.g. JoseSessionTokenProvider with RSA-OAEP key wrap) and via SAML redirect/POST binding token inflation — in both cases decompression happens before/independent of trust validation.

Fix: Added a configurable maximum inflated-size cap (default 10 MiB, org.apache.cxf.compression-max-inflated-size system property) to CompressionUtils.inflate(); aborts with DataFormatException once exceeded. Users are recommended to upgrade to versions 4.2.4 or 4.1.9 or 3.6.13, which fix this issue.

Improper enforcement of single-use authorization code semantics in the JPA OAuth2 authorization code grant provider in Apache CXFallows a remote attacker to obtain multiple valid access tokens from a single authorization code via concurrent token exchange requests that race the non-atomic find-then-delete operation against a shared relational database under READCOMMITTED isolation. Users are recommended to upgrade to versions 4.2.4 or 4.1.9 or 3.6.13, which fixes this issue.

The maxage authentication-freshness check in OidcClientCodeRequestFilter was inoperative due to a milliseconds/seconds unit mismatch and an inverted comparison polarity. Any relying party using setMaxAgeOffset to enforce re-authentication would silently accept sessions of any age, bypassing step-up authentication policies. Users are recommended to upgrade to versions 4.2.4 or 4.1.9 or 3.6.13, which fix this issue.

Severity: low

Affected versions:

- Apache CXF 4.2.0 before 4.2.4 - Apache CXF 4.0.0 before 4.1.9 - Apache CXF before 3.6.13

Description:

By default, StaxUtils placed no limit on the total number of elements or the total number of characters in an XML document. A very large request could therefore use a lot of memory and CPU during parsing, especially where CXF builds a DOM from the input (for example SAAJ or WS-Security), and could cause a denial of service when no request size limit was configured. Both limits now have defaults: the maximum element count is 100 × maxChildElements (5,000,000 by default), and the maximum document size is 256M characters. Applications that process larger documents can raise the limits with the org.apache.cxf.stax.maxElementCount and org.apache.cxf.stax.maxXMLCharacters properties. Users are recommended to upgrade to versions 4.2.4 or 4.1.9 or 3.6.13, which fix this issue.

Credit:

Wanxin Yin (yaklang.io) <yhellow123456 () gmail com> (finder)

References:

https://cxf.apache.org/ https://www.cve.org/CVERecord?id=CVE-2026-108039

Severity: important

Affected versions:

- Apache CXF 4.2.0 before 4.2.4 - Apache CXF 4.0.0 before 4.1.9 - Apache CXF before 3.6.13

Description:

In Apache CXF, the Netty-based HTTP client transport (cxf-rt-transports-http-netty-client) did not verify that the hostname in the server’s TLS certificate matched the host being called. This applied over both HTTP/1.1 and HTTP/2, even when disableCNCheck was left at its default value of false. The certificate chain was validated against the configured trust store, but the endpoint’s identity was not. A network attacker able to intercept traffic could present any certificate trusted by the client, such as a publicly issued certificate for a domain they control, and impersonate the target service. They could then read or modify the exchanged messages, including credentials.  Users are recommended to upgrade to versions 4.2.4 or 4.1.9 or 3.6.13, which fix this issue.

Credit:

This issue was found using Claude agents to study the security of open-source projects (finder)

References:

https://cxf.apache.org/ https://www.cve.org/CVERecord?id=CVE-2026-107938

Severity: low

Affected versions:

- Apache CXF 4.2.0 before 4.2.4 - Apache CXF 4.0.0 before 4.1.9 - Apache CXF before 3.6.13

Description:

In Apache CXF, the parser for multipart/MTOM attachment part headers did not fully enforce the configured attachment-max-header-size (default 300 characters) and attachment-headers-max-count (default 500) limits. The size limit was applied only to each physical line, not to a header value built from continuation lines or to the combined values of a repeated header. The count limit was checked against the number of distinct header names, not the total number of header lines. A remote, unauthenticated attacker could send a multipart request with very large folded or repeated part headers. The server would then allocate memory without bound, causing a denial of service.  Users are recommended to upgrade to versions 4.2.4 or 4.1.9 or 3.6.13, which fix this issue.

Credit:

This issue was found using Claude agents to study the security of open-source projects and independently by Mike Read (github.com/Michael-JRead) (finder)

References:

https://cxf.apache.org/ https://www.cve.org/CVERecord?id=CVE-2026-107937

Severity: moderate

Affected versions:

- Apache CXF 4.2.0 before 4.2.4 - Apache CXF 4.0.0 before 4.1.9 - Apache CXF before 3.6.13

Description:

Improper Verification of Cryptographic Signature vulnerability in Apache CXF's JAX-RS XML Security module. The JAX-RS XML Signature interceptors (XmlSigInHandler, XmlSigInInterceptor and the streaming XmlSecInInterceptor) did not ensure that the XML passed to the application was covered by the signature. An attacker with any document signed by a trusted key could wrap it in unsigned content, which the application would then treat as signed. Users are recommended to upgrade to versions 4.2.4 or 4.1.9 or 3.6.13, which fix this issue.

Credit:

This issue was found using Claude agents to study the security of open-source projects and independently by Guanping Zhang (finder)

References:

https://cxf.apache.org/ https://www.cve.org/CVERecord?id=CVE-2026-100227

Severity: important

Affected versions:

- Apache CXF 4.2.0 before 4.2.4 - Apache CXF 4.0.0 before 4.1.9 - Apache CXF before 3.6.13

Description:

In Apache CXF, STSTokenValidator checks whether a SAML assertion is signed by a trusted certificate before deciding to send it to the STS. That result was stored in one object shared by all requests, so one request could read another's result. A remote, unauthenticated attacker could send a forged assertion signed with an untrusted certificate while legitimate requests were being processed, and it could be accepted as trusted without ever reaching the STS. Only services that use STSTokenValidator to validate SAML tokens without alwaysValidateToSts set are affected.  Users are recommended to upgrade to versions 4.2.4 or 4.1.9 or 3.6.13, which fix this issue.

Credit:

MopMonk-AI (finder)

References:

https://cxf.apache.org/ https://www.cve.org/CVERecord?id=CVE-2026-97791

Severity: important

Affected versions:

- Apache CXF 4.2.0 before 4.2.4 - Apache CXF 4.0.0 before 4.1.9 - Apache CXF before 3.6.13

Description:

Apache CXF's STSTokenValidator and Security Token Service (STS) cached validated security tokens under a non-cryptographic 32-bit hash of the token (Java Arrays.hashCode/hashCode()), and treated a cache hit as proof that the presented token had already been validated. An attacker could craft a token (for example a UsernameToken or a self-signed SAML Assertion) whose hash collides with a cached entry. The token would then be accepted without password validation, signature trust verification or a call to the STS. This could let the attacker authenticate as another user and, through STS token validation or renewal, obtain STS-signed tokens for that identity. Users are recommended to upgrade to versions 4.2.4 or 4.1.9 or 3.6.13, which fix this issue.

Credit:

MopMonk-AI (finder)

References:

https://cxf.apache.org/ https://www.cve.org/CVERecord?id=CVE-2026-97468

A race condition in JCacheCodeDataProvider allows an attacker to redeem a single authorization code multiple times via concurrent requests, resulting in the issuance of multiple distinct, valid access tokens. Users are recommended to upgrade to versions 4.2.3, 4.1.8 or 3.6.12, which fix this issue.

In Apache CXF's OAuth2 Dynamic Client Registration endpoint, the authorization server accepts and stores the scope value supplied in the client registration request verbatim, without validating it against an AS-defined allowlist. This could lead to a client self-assigning privileged scopes at registration time. Users are recommended to upgrade to versions 4.2.3 or 4.1.8 or 3.6.12, which fix this issue.

Apache CXF's JwtRequestCodeFilter copies all claims from a signed request JWT into the authorization parameter map without excluding security-sensitive parameters. A client that can produce a validly-signed request JWT (e.g., one whose clientsecret is known or compromised) can thereby substitute the codechallenge, codechallengemethod, nonce, and state values that were set in the outer HTTP request, undermining PKCE integrity and OpenID Connect replay protection. Users are recommended to upgrade to versions 4.2.3 or 4.1.8 or 3.6.12, which fix this issue.

Apache CXF’s OIDC relying-party token validation could accept self-issued ID tokens without enforcing required claim checks (issuer/subject/audience/time and subjwk binding), enabling authentication bypass with crafted tokens. However, note that self-issued ID tokens are not accepted by default in the validator. Users are recommended to upgrade to versions 4.2.3 or 4.1.8 or 3.6.12, which fixes this issue.

In Apache CXF's DefaultEncryptingCodeDataProvider, a captured authorization code can be redeemed an unlimited number of times due to a flaw in the implementation of the removeCodeGrant functionality. This violates the RFC requirement that "The authorization code MUST NOT be used more than once." Users are recommended to upgrade to versions 4.2.3 or 4.1.8 or 3.6.12, which fix this issue.

In Apache CXF's DefaultEncryptingOAuthDataProvider, revoked access tokens still decrypt successfully, and TokenIntrospectionService reports active:true. The same applies to refresh tokens. This violates the RFC stipulations that 'The authorization server MUST invalidate the token.' and 'introspection of a revoked token MUST return {"active":false}'. Users are recommended to upgrade to versions 4.2.3 or 4.1.8 or 3.6.12, which fix this issue.

Severity: low

Affected versions:

- Apache CXF (org.apache.cxf:cxf-rt-rs-security-sso-oidc) 4.2.0 before 4.2.3 - Apache CXF (org.apache.cxf:cxf-rt-rs-security-sso-oidc) 4.0.0 before 4.1.8 - Apache CXF (org.apache.cxf:cxf-rt-rs-security-sso-oidc) before 3.6.12

Description:

Apache CXF’s OIDC relying-party token validation could accept self-issued ID tokens without enforcing required claim checks (issuer/subject/audience/time and subjwk binding), enabling authentication bypass with crafted tokens. However, note that self-issued ID tokens are not accepted by default in the validator. Users are recommended to upgrade to versions 4.2.3 or 4.1.8 or 3.6.12, which fixes this issue.

Credit:

Guanping Zhang reported this vulnerability. (finder)

References:

https://cxf.apache.org/ https://www.cve.org/CVERecord?id=CVE-2026-65583

Apache CXF reads a top-level WSDL through its hardened StaxUtils path, which disables XML DTDs and external entities. However, any <wsdl:import> or <xsd:import> referenced from that top-level WSDL is handed off to WSDL4J, which does not disable DOCTYPE declarations or external entities. As a result, the protections applied to the top-level document do not extend to imported documents, leaving imported WSDL/XSD content vulnerable to XML External Entity (XXE) attacks. Users are recommended to upgrade to versions 4.2.3 or 4.1.8 or 3.6.12, which fix this issue.

The OpenID Connect Core 1.0 specification mandates that the RP MUST validate the chash parameter when operating in the Hybrid Flow. If an Apache CXF RP is integrated with a non-compliant or misconfigured Identity Provider (IdP) that omits the chash, the RP becomes vulnerable to Authorization Code Substitution/Injection attacks. Users are recommended to upgrade to versions 4.2.3 or 4.1.8 or 3.6.12, which fix this issue.

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.

An incomplete fix for CVE-2026-50645 means that it is still possible to perform a denial of service attack on Apache CXF by sending a message with many attachment headers. Users are recommended to upgrade to versions 4.2.3 or 4.1.8 or 3.6.12, which fix this issue.

Apache CXF allows to set a limit on the number of form parameters in a JAX-RS message via the "maxFormParameterCount" configuration option. However, no default limit is set which may lead to denial of service attacks when processing  requests with very large numbers of form parameters. Users are recommended to upgrade to versions 4.2.3 or 4.1.8 or 3.6.12, which fix this issue by using a default limit of 500 parameters.

Apache CXF allows to control the maximum attachment size via the "attachment-max-size". Prior to Apache CXF 4.2.3 and 4.1.8 and 3.6.12, there was no default placed on this size, meaning that a denial of service attack is possible if the user doesn't explicitly set the limit. Users should update to Apache CXF 4.2.3 or 4.1.8 or 3.6.12 which fixes this problem by imposing a default attachment size limit of 50mb.