CVE-2026-106459 in plugin-scaffolder-backend-module-sentry
Summary
by MITRE • 10/07/2026
Backstage is an open framework for building developer portals. From 0.3.0 until 0.3.8, the @backstage/plugin-scaffolder-backend-module-sentry package is affected by improper input validation in sentry scaffolder actions. An authenticated internal user who can execute the affected actions may cause the backend to contact unintended destinations and disclose Sentry integration credentials. Subsequent impact depends on network reachability and the privileges granted to the configured token. This issue is fixed in version 0.3.8.
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Analysis
by VulDB Data Team • 10/07/2026
The vulnerability identified within Backstage versions ranging from 0.3.0 through 0.3.8 resides specifically in the @backstage/plugin-scaffolder-backend-module-sentry package, which facilitates integration with Sentry for error tracking and monitoring during software development workflows. This component is responsible for handling scaffolding actions that interact with external services to report build or runtime errors. The core technical flaw stems from improper input validation within these scaffolder actions, where the system fails to adequately sanitize or verify user-supplied data before processing it in network requests directed toward Sentry infrastructure.
From a technical perspective, this lack of rigorous input validation allows an authenticated internal user who possesses permissions to execute affected scaffolding actions to manipulate the destination endpoints contacted by the backend service. By injecting maliciously crafted inputs into the action parameters, an attacker can redirect outbound traffic from the Backstage backend server to unintended destinations under their control or influence. This behavior effectively turns the legitimate integration mechanism into a vector for unauthorized network interactions, bypassing standard access controls that would otherwise restrict such communications to approved Sentry endpoints only.
The operational impact of this vulnerability is significant due to the potential disclosure of sensitive credentials associated with the Sentry integration. Since the backend server typically holds API keys or tokens required to authenticate with Sentry services, redirecting these requests allows an attacker to intercept and exfiltrate these secrets if they control the unintended destination. The severity of the subsequent compromise depends heavily on network reachability and the specific privileges granted to the configured Sentry token. If the token has broad permissions, such as access to multiple projects or sensitive error data, the exposure could lead to further exploitation including information disclosure, integrity manipulation, or even lateral movement within the development infrastructure if those credentials are reused elsewhere.
This vulnerability aligns with CWE-20 Improper Input Validation and CWE-918 Server-Side Request Forgery (SSRF), as it involves failing to validate user input which leads to unauthorized server-side network requests. In terms of adversary tactics, this behavior corresponds to ATT&CK technique T1557 Adversary-in-the-Middle or potentially T1046 Network Service Discovery depending on the specific exploitation path and intent, though primarily it represents a mechanism for credential theft via SSRF-like conditions within an internal service context.
To mitigate this risk, organizations must immediately upgrade to Backstage version 0.3.8 or later where the input validation logic has been corrected to ensure that only authorized Sentry endpoints are contacted during scaffolding operations. Additionally, administrators should rotate any Sentry API keys and tokens associated with affected installations to invalidate potentially compromised credentials. Implementing strict network egress policies using firewalls or proxy servers can also help restrict backend services from communicating with unauthorized external destinations, providing a defense-in-depth layer against similar SSRF-style vulnerabilities in other components of the platform.