RUSTSEC-2026-0068: tar-rs incorrectly ignores PAX size headers if header size is nonzero #217

Versions 0.4.44 and below of tar-rs have conditional logic that skips the PAX
size header in cases where the base header size is nonzero.

As part of CVE-2025-62518, the astral-tokio-tar
project was changed to correctly honor PAX size headers in the case where it
was different from the base header. This is almost the inverse of the
astral-tokio-tar issue.

Any discrepancy in how tar parsers honor file size can be used to create
archives that appear differently when unpacked by different archivers. In this
case, the tar-rs (Rust tar) crate is an outlier in checking for the header size
— other tar parsers (including e.g. Go archive/tar) unconditionally
use the PAX size override. This can affect anything that uses the tar crate to
parse archives and expects to have a consistent view with other parsers.

This issue has been fixed in version 0.4.45.