CVE-2026-44930: Apache CXF Information Disclosure Flaw

CVE-2026-44930 Overview

CVE-2026-44930 is an LDAP injection vulnerability in the LDAP Certificate repository of the XML Key Management Specification (XKMS) server in Apache CXF. An unauthenticated attacker can craft malicious input that manipulates LDAP search filters to retrieve arbitrary certificates from the repository. The flaw is classified under CWE-90: Improper Neutralization of Special Elements used in an LDAP Query. Apache has released fixed versions 4.2.1, 4.1.6, and 3.6.11 to address the issue.

Critical Impact

Remote, unauthenticated attackers can extract arbitrary X.509 certificates from the XKMS LDAP repository, undermining the trust assumptions of any service relying on those certificates.

Affected Products

• Apache CXF versions prior to 3.6.11
• Apache CXF versions prior to 4.1.6
• Apache CXF 4.2.0 (fixed in 4.2.1)

Discovery Timeline

• 2026-05-22 - CVE-2026-44930 published to NVD
• 2026-05-22 - Last updated in NVD database

Technical Details for CVE-2026-44930

Vulnerability Analysis

Apache CXF ships an XKMS server component that uses an LDAP-backed repository to store and look up X.509 certificates. The repository builds LDAP search filters from caller-supplied input without adequately neutralizing LDAP metacharacters. An attacker who can reach the XKMS endpoint can therefore inject filter syntax such as wildcards or boolean operators into the query.

Because XKMS exposes certificate lookup operations over the network, the attack requires no authentication and no user interaction. Successful exploitation allows the attacker to widen the result set returned by the LDAP backend and retrieve certificates that the requestor was never authorized to obtain. Disclosure of certificate material can support downstream attacks against signature verification, mutual TLS, and key management workflows that depend on the XKMS service.

Root Cause

The root cause is improper neutralization of special elements used in an LDAP query [CWE-90]. The LDAP Certificate repository concatenates untrusted input into search filter expressions instead of escaping characters such as *, (, ), \, and \0 per RFC 4515. As a result, request parameters intended to identify a single certificate can be reshaped into broader filter clauses.

Attack Vector

The attack vector is purely network-based against the XKMS service endpoint. An attacker submits a crafted XKMS Locate or Validate request containing LDAP filter metacharacters in the identifier field. The server forwards the unsanitized value into an LDAP filter such as (cn=<input>), where an injected wildcard like * causes the directory to return every certificate entry. Because no credentials are required, any party with network reach to the XKMS server can perform the extraction.

No public proof-of-concept exploit is currently available, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog. See the Apache Mailing List Discussion and OpenWall OSS Security Update for vendor details.

Detection Methods for CVE-2026-44930

Indicators of Compromise

• XKMS requests containing LDAP metacharacters such as *, )(, |, or & in identifier or subject fields.
• Unusually large XKMS response payloads returning multiple certificates for a single lookup request.
• LDAP server logs showing search filters originating from the CXF XKMS service that resolve to wildcard or disjunctive expressions.

Detection Strategies

• Inspect application logs for XKMS Locate and Validate requests where the supplied key identifier contains LDAP filter syntax.
• Correlate XKMS request volume with backing LDAP query result counts to identify enumeration patterns.
• Deploy WAF or API gateway rules that flag LDAP injection signatures targeting the XKMS endpoint path.

Monitoring Recommendations

• Enable verbose audit logging on the LDAP directory backing the XKMS repository and ship logs to a centralized analytics platform.
• Alert on bursts of certificate retrievals from a single client IP or session within a short time window.
• Monitor egress traffic from the XKMS host for unexpected bulk transfers of certificate data.

How to Mitigate CVE-2026-44930

Immediate Actions Required

• Upgrade Apache CXF to version 4.2.1, 4.1.6, or 3.6.11 depending on the deployed branch.
• Restrict network access to the XKMS endpoint to trusted clients using firewall or service mesh policies.
• Audit the LDAP certificate repository for unauthorized read activity since the service was first exposed.

Patch Information

Apache CXF maintainers fixed the vulnerability in releases 4.2.1, 4.1.6, and 3.6.11. The patched versions properly escape LDAP filter metacharacters before constructing search queries against the certificate repository. Upgrade guidance is documented in the Apache Mailing List Discussion.

Workarounds

• Disable the XKMS server component if it is not required by the deployment.
• Place the XKMS endpoint behind authenticated reverse proxy access and require mutual TLS for callers.
• Apply input validation at an API gateway to reject identifiers containing LDAP filter metacharacters until the upgrade is complete.