Peazip

Path Traversal (CWE-22) in the execute_obj function of the archive object viewer (peach.pas) in PeaZip 11.2.0 and earlier on Windows allows an attacker who convinces a victim to preview an entry of a crafted archive via the "Preview with... -> Associated application" action (Shift+Ctrl+O) to execute an arbitrary program already present on the victim's system, with no warning dialog. The function validates only outname (PeaZip's own temporary directory) with checkfiledirname, while the string actually executed is the concatenation outname+tempstring; tempstring is taken verbatim from the archive entry name (StringGridList.Cells[12,...]) and is never validated. checkfiledirname (list_utils.pas) rejects control and reserved characters in the file name but performs no ".." path-containment check, so an entry named ../../../../Windows/System32/calc.exe escapes the extraction directory and is passed to cp_open -> ShellExecuteW; the extracting backend (7-Zip) strips the traversal while the opener does not. In addition, the SECEXTCONST dangerous-extension confirmation prompt is implemented only in the double-click handler (grid_obj_open) and not on this preview route, so an executable inside an archive reaches ShellExecuteW unannounced, and where the prompt does fire it names the entry's display name rather than the resolved path that will run. Arbitrary code execution was demonstrated with a proof of concept against official PeaZip builds, confirmed on two archive formats (.zip and .tar) to show the defect is in PeaZip's own path handling and not in a single format parser.

Published: 2026-10-15T12:00:49.995Z
Updated: 2026-10-15T13:11:13.654Z

Incomplete List of Disallowed Inputs (CWE-184) in the dangerous-extension confirmation of the archive object viewer (peach.pas, grid_obj_open) in PeaZip 10.5.0 through 11.2.0 on Windows allows an attacker who convinces a victim to open an entry of a crafted archive to execute a program, or an arbitrary command, with no confirmation dialog. The prompt (Do you want to run this file?) is gated by SECEXTCONST, a hard-coded list of seven extensions (exe cmd msi bat ps1 vbs reg); the check is an exact string comparison of the entry extension against that list, so it answers only whether the extension is one of the seven and never whether the shell will execute the file. Shell-executable and scripting-host types that Windows runs through ShellExecuteW are absent from the list, among them .url and .lnk. An archived Windows Internet Shortcut (.url) whose URL line is attacker-controlled is launched with no prompt, while the byte-identical content in an entry named .bat does raise the warning in the same session. A .lnk entry raises the ceiling from launching a program to running a command line, because a Windows shortcut carries arguments: a proof-of-concept shortcut targeting cmd.exe with an attacker-chosen command line executed with no prompt. The shortcut target is not confined to the local disk; the shell also resolved an attacker-named UNC path (fetching a remote payload was only attempted, not demonstrated). No privilege escalation; everything runs as the user who opened the archive.

Published: 2026-10-15T13:30:13.885Z
Updated: 2026-10-16T18:47:51.852Z