astral-tokio-tar Vulnerable to PAX Header Desynchronization

Versions of astral-tokio-tar prior to 0.5.6 contain a boundary parsing vulnerability that allows attackers to smuggle additional archive entries by exploiting inconsistent PAX/ustar header handling. When processing archives with PAX-extended headers containing size overrides, the parser incorrectly advances stream position based on ustar header size (often zero) instead of the PAX-specified size, causing it to interpret file content as legitimate tar headers. This vulnerability was disclosed to multiple Rust tar parsers, all derived from the original async-tar fork of tar-rs. For additional information see [Edera's blog post](https://edera.dev/stories/tarmageddon).

Source published

21 Oct 2025 12:00:00 UTC

Source modified

12 Oct 2026 18:00:11 UTC

Observed here

24 Oct 2026 13:19:54 UTC

Source terms

OSV · upstream source license applies

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CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N