CVE-2023-36829 in Sentry
Summary
by MITRE • 07/07/2023
Sentry is an error tracking and performance monitoring platform. Starting in version 23.6.0 and prior to version 23.6.2, the Sentry API incorrectly returns the `access-control-allow-credentials: true` HTTP header if the `Origin` request header ends with the `system.base-hostname` option of Sentry installation. This only affects installations that have `system.base-hostname` option explicitly set, as it is empty by default. Impact is limited since recent versions of major browsers have cross-site cookie blocking enabled by default. However, this flaw could allow other multi-step attacks. The patch has been released in Sentry 23.6.2.
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Analysis
by VulDB Data Team • 07/25/2023
The vulnerability described in CVE-2023-36829 affects the Sentry error tracking and performance monitoring platform, specifically targeting installations running versions 23.6.0 through 23.6.1. This flaw represents a misconfiguration in the Cross-Origin Resource Sharing (CORS) implementation that could potentially enable unauthorized access to sensitive data. The vulnerability stems from the API's improper handling of the access-control-allow-credentials header, which is a critical component in web security that controls how browsers handle cross-origin requests with credentials. When the Origin request header contains a specific pattern matching the system.base-hostname option, the API incorrectly returns the access-control-allow-credentials: true header, creating a potential security risk.
The technical flaw manifests when Sentry installations have explicitly configured the system.base-hostname option, which is empty by default in standard deployments. This configuration parameter defines the base hostname for the Sentry installation, and when an incoming request contains an Origin header that ends with this configured hostname, the system incorrectly grants credential access permissions. This behavior violates the fundamental security principle of CORS where credentials should only be allowed for trusted origins, not arbitrary patterns that match partial hostname components. The vulnerability aligns with CWE-621, which addresses improper handling of cross-origin resource sharing, and represents a specific implementation flaw in the CORS policy enforcement mechanism.
The operational impact of this vulnerability is constrained by modern browser security measures, as recent versions of major browsers have implemented cross-site cookie blocking by default, limiting the immediate exploitation potential. However, the flaw remains concerning because it could enable sophisticated multi-step attack vectors that leverage the misconfigured CORS settings as part of a broader exploitation strategy. Attackers could potentially use this vulnerability to bypass security controls in specific scenarios where the browser's default protections are circumvented or where legacy browser versions are in use. The vulnerability affects organizations that have explicitly configured their Sentry installations with base hostname settings, making it particularly relevant for enterprise deployments that require specific domain configurations.
Organizations should immediately upgrade to Sentry version 23.6.2, which contains the necessary patch to address this vulnerability. The fix resolves the improper CORS header handling by ensuring that the access-control-allow-credentials header is only returned when the Origin header matches the configured base hostname exactly, rather than allowing pattern matching. Security teams should also review their Sentry configuration files to ensure that the system.base-hostname option is properly set and validated, and consider implementing additional monitoring for unusual Origin header patterns in API requests. This vulnerability demonstrates the importance of proper CORS configuration management and the potential risks associated with overly permissive cross-origin policies, particularly in security-sensitive applications like error tracking platforms that may handle sensitive operational data. The ATT&CK framework categorizes this as a potential technique for privilege escalation or information disclosure through web application vulnerabilities, highlighting the need for comprehensive security testing of API endpoints and CORS implementations.