Bug 2493582 (CVE-2026-57966)

Summary: CVE-2026-57966 spice-vdagent: Path traversal in file transfer via unsanitized filename
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A path traversal vulnerability was found in spice-vdagent. This flaw allows a malicious or compromised SPICE host to write arbitrary files to any location on the guest operating system. This occurs because the filename provided by the SPICE host during file transfers is not properly sanitized before being used. An attacker could exploit this to write to sensitive locations with the privileges of the spice-vdagent process, typically the logged-in user. This issue requires the SPICE host to be untrusted or compromised for exploitation.
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Bug Depends On: 2494105    
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Description OSIDB Bzimport 2026-06-26 15:37:10 UTC 
A path traversal vulnerability was found in spice-vdagent. In src/vdagent/file-xfers.c, the filename received from the SPICE host in file transfer metadata is used directly in g_build_filename() without any sanitization (file-xfers.c:138-139, 190). The g_build_filename() function has documented behavior where if the second argument is an absolute path (starts with '/'), the first argument (save_dir) is silently discarded. Additionally, '..' components in relative paths are not stripped, enabling directory traversal.

This allows a malicious SPICE host to write arbitrary files at arbitrary paths on the guest filesystem, with the privileges of the spice-vdagent process (typically the logged-in user).

Note: this is distinct from CVE-2017-15108, which was about unescaped save_dir passed to system() (command injection, CWE-78). This finding concerns the file name parameter not being sanitized for path traversal (CWE-22) — different input variable, different vulnerability class. Exploitation requires a malicious or compromised SPICE host.