CVE-2026-64958 in CXF
Summary
by MITRE • 08/06/2026
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.
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Analysis
by VulDB Data Team • 08/06/2026
The vulnerability described in CVE-2026-50645 represents a persistent denial of service weakness within Apache CXF messaging framework that stems from inadequate handling of message attachment headers. This flaw allows malicious actors to exploit the system by crafting specially formatted messages containing an excessive number of attachment headers, thereby overwhelming the processing capabilities of affected servers and rendering them unavailable to legitimate users. The issue specifically targets the message parsing mechanisms within Apache CXF's web services implementation where insufficient validation occurs during header processing, creating a pathway for resource exhaustion attacks.
The technical nature of this vulnerability aligns with CWE-400, which categorizes it as an uncontrolled resource consumption flaw, and can be mapped to ATT&CK technique T1498 under Network Denial of Service. The root cause lies in the insufficient bounds checking and resource management within the message processing pipeline where attachment headers are parsed without proper limits on quantity or size. This allows attackers to send messages that trigger excessive memory allocation and processing cycles, ultimately leading to system instability and service disruption.
The operational impact of this vulnerability extends beyond simple service interruption as it can affect critical business processes relying on Apache CXF for web services communication. Organizations utilizing affected versions face potential downtime, increased system load, and possible cascading failures when the denial of service conditions are triggered. The attack vector is particularly concerning because it requires minimal sophistication to execute, making it accessible to threat actors with basic network knowledge while still delivering significant operational disruption.
Organizations should prioritize upgrading their Apache CXF implementations to versions 4.2.3, 4.1.8, or 3.6.12 as recommended by the vendor, as these releases contain comprehensive fixes addressing the header parsing limitations. The upgrade process should include thorough testing of existing web service integrations to ensure compatibility with the patched implementation. Additionally, network-level mitigations such as message size limits and attachment header rate limiting can provide additional protective layers while the formal upgrades are being implemented. Security teams should also monitor for potential exploitation attempts through log analysis and implement proper alerting mechanisms to detect unusual header patterns that may indicate attempted attacks against this vulnerability.