CVE-2026-16517

A signed integer overflow vulnerability was found in libarchive's ZIP writer. In the archive_write_zip_header function in archive_write_set_format_zip.c, when ZIP encryption is enabled and the entry file size is close to INT64_MAX, the addition of the encryption overhead to the entry size overflows int64_t, resulting in undefined behavior. This could lead to incorrect Zip64 extension decisions or potential memory corruption.

Red Hat Product Security rates this issue as Low severity. The vulnerability is in the ZIP write path only and requires both ZIP encryption to be enabled and a file size near INT64_MAX, making real-world exploitation highly unlikely. The resulting undefined behavior could theoretically cause incorrect Zip64 extension decisions or a crash, but the conditions are too contrived for practical exploitation.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.