CVE-2026-78242 in APISIX
Summary
by MITRE • 10/01/2026
Insertion of sensitive information into log file vulnerability in Apache APISIX.
This vulnerability can cause the unmasked header value to be written to the log sink under a certain response structure.
This issue affects Apache APISIX: 3.17.0.
Users are recommended to upgrade to version 3.18.0, which fixes the issue.
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Analysis
by VulDB Data Team • 10/01/2026
The vulnerability identified in Apache APISIX versions prior to 3.18.0 represents a critical information disclosure flaw rooted in improper log sanitization practices. As an API gateway and reverse proxy, Apache APISIX is designed to handle high volumes of traffic while maintaining detailed observability through logging mechanisms. However, under specific response structures, the application fails to adequately mask sensitive header values before writing them to the configured log sink. This oversight results in the unmasked transmission or storage of potentially confidential data within log files that may be accessible to a broader set of users than intended for administrative purposes alone. The core technical flaw lies in the logging middleware's failure to apply consistent redaction rules across all HTTP header fields, particularly when certain response configurations trigger specific code paths where sensitive metadata is captured without filtering.
From a security architecture perspective, this issue aligns with CWE-532, which categorizes information exposure through log files as a significant risk vector. Log files are often aggregated into centralized logging systems such as ELK stacks or Splunk for analysis and monitoring purposes. These systems frequently have broader access permissions than the application servers themselves to facilitate debugging and performance tuning across multiple services. Consequently, sensitive headers containing authentication tokens, session identifiers, personal identifiable information, or internal network topology details can be inadvertently persisted in plaintext. This persistence creates a long-term attack surface where attackers who gain read access to log storage infrastructure can harvest credentials or other secrets without needing direct application-level exploitation capabilities.
The operational impact of this vulnerability extends beyond immediate credential theft. It facilitates unauthorized data collection that violates privacy regulations such as GDPR or HIPAA if personal data is involved in the headers. Furthermore, it aids reconnaissance efforts by exposing internal API structures and authentication mechanisms to potential adversaries. In a zero-trust environment, where logs are often shared across security operations centers (SOC) and development teams, this flaw undermines the principle of least privilege regarding sensitive metadata. Attackers can leverage these exposed values for session hijacking or lateral movement within the network infrastructure if the logged headers contain valid authentication tokens that have not yet expired.
Mitigation strategies must prioritize immediate remediation through version upgrades alongside defensive logging configurations. The primary and most effective solution is to upgrade Apache APISIX to version 3.18.0 or later, where this specific logic error in header masking has been corrected by the development team. In environments where upgrading is not immediately feasible, administrators should implement compensating controls at the log ingestion layer. This includes configuring external log parsers or forwarders such as Fluentd or Logstash to strip sensitive headers like Authorization, Cookie, and Set-Cookie before they are written to disk or sent to remote logging services. Additionally, organizations should audit their current logging configurations to ensure that only necessary fields are logged and that access controls on log storage locations are strictly enforced to limit exposure of any residual sensitive data.
This vulnerability also relates to ATT&CK technique T1505.003, which involves server log components being used for persistence or collection of information. By ensuring that logs do not contain plaintext secrets, organizations reduce the effectiveness of this tactic in post-exploitation phases. Security teams should routinely review logging policies to align with industry best practices such as NIST SP 800-92 guidelines on computer security event logging, which emphasize minimizing the inclusion of sensitive data in log entries. Regular penetration testing and automated scanning for information leakage in logs can further help detect similar misconfigurations across the infrastructure stack before they are exploited by malicious actors seeking to compromise system integrity or confidentiality.