Adm-zip versions 0.5.9 through 0.6.0 follow symbolic links when extracting archives. The utility sanitizes file names by comparing string representations rather than resolving links, and writes data to paths resolved by the operating system without the O_NOFOLLOW flag. If a component of the extraction destination is already a symbolic link that points outside the intended root, extraction will write through that link, overwriting the target file and then changing its permissions. This flaw allows an attacker to replace any file the extracting process can write to, without any traversal characters in the archive itself.

The issue affects the adm-zip project released by cthackers, specifically the 0.5.9, 0.5.10, 0.5.11, and 0.6.0 releases. Any deployment that relies on those versions for archive extraction is vulnerable.

The CVSS score of 6.8 indicates moderate severity. The EPSS score is not provided and the vulnerability is not listed in the CISA KEV catalog, suggesting no known large‐scale exploitation currently. However, the flaw can be leveraged by an attacker who can place a symbolic link in the extraction directory—e.g., in a shared temporary folder, a repeatable CI workspace, or any directory the process writes to—thereby enabling the attacker to overwrite arbitrary files like configuration files or executables. The exploit requires local write access to the extraction path and any privileges the extraction process runs with.