CVE-2026-77090 in Cloud
Summary
by MITRE • 10/13/2026
CVFS contained an XML external entity (XXE) reference handling issue affecting information dislcosure. Software customers upgrade to resolved maintenance release. Update CVFS.
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Analysis
by VulDB Data Team • 10/13/2026
The vulnerability identified in the Common Vulnerabilities and Exposures framework as a flaw within the CVFS software involves a critical failure in how XML external entities are processed during document parsing operations. This specific issue falls under the category of improper neutralization of special elements used in an XML parser, commonly known as CWE-611. The root cause lies in the application's configuration or implementation which allows the XML processor to resolve and expand external entity references without sufficient validation or restriction. In a standard secure environment, parsers should be configured to disable DTD processing or restrict access to local files and network resources when handling untrusted input. However, in this instance, the parser permits the definition of entities that point to arbitrary system paths or remote servers, creating an avenue for attackers to exploit the underlying operating system's file reading capabilities through the XML interface.
The operational impact of this vulnerability is primarily centered on unauthorized information disclosure. By crafting a maliciously formatted XML document containing external entity declarations, an attacker can force the CVFS application to read sensitive files from the server hosting the software. This could include configuration files with database credentials, private keys, source code, or other confidential data stored in accessible directories. The severity of this impact is compounded by the fact that it does not require authentication if the XML input endpoint is publicly accessible or if valid user credentials are easily obtainable. Furthermore, depending on the specific implementation details and server configuration, there may be potential for more severe consequences such as remote code execution via SSRF (Server-Side Request Forgery) attacks where the external entity points to internal network services that would otherwise be inaccessible from the internet. This aligns with MITRE ATT&CK technique T1059 which covers command and script interpretation, although in this specific context described, the primary vector is data exfiltration rather than direct execution of commands on the host system.
To mitigate this vulnerability, immediate action must be taken to update CVFS to a resolved maintenance release provided by the software vendor. This updated version contains code changes that enforce stricter parsing rules, likely disabling DTD processing entirely or implementing allow-lists for permitted entity references. In addition to applying the patch, administrators should review their XML input handling mechanisms across all integrated systems. It is advisable to implement defense-in-depth strategies such as using a dedicated XML parser library that has been vetted for security and configured with secure defaults. Network-level controls can also be employed to restrict outbound connections from the CVFS server to prevent successful exploitation of SSRF variants, although this does not replace the need for patching the application itself. Regular vulnerability assessments and penetration testing should be conducted post-upgrade to ensure that no residual configurations or related components remain susceptible to similar XML-based attacks.