astral-tokio-tar has a PAX Header Desynchronization issue

### Impact Versions of astral-tokio-tar prior to 0.6.2 contain a PAX header interpretation bug that allows manipulated entries to be made selectively visible or invisible during extraction with astral-tokio-tar versus other tar implementations. An attacker could use this differential to smuggle unexpected files onto a victim's filesystem. ### Details When a tar stream contains multiple "header" entries prior to a file entry, astral-tokio-tar applies the PAX header (`x`) to the next entry in the stream, regardless of type. For example, a stream of `x -> L -> file` (PAX, GNU longname, file) would result in `x`'s extensions being applied to `L` rather than to `file`. [Per POSIX pax](https://pubs.opengroup.org/onlinepubs/9799919799/utilities/pax.html), this is incorrect: a PAX header always applies to a file entry, not any intermediary entries. See the "pax Header Block" section for the specific prescription there. As a result of this, an attacker can contrive a tar containing a sequence of tar headers such that astral-tokio-tar applies the PAX header's size extension to the next header in sequence, effectively desynchronizing the stream and enabling astral-tokio-tar specific skippage/extraction of members. In other words, a file can be contrived to extract differently on astral-tokio-tar than on other tar parsers. ### Patches Versions 0.6.2 and newer of astral-tokio-tar address this differential. ### Workarounds Users are advised to upgrade to version 0.6.1 or newer to address this advisory. There is no workaround other than upgrading. Users should experience no breaking changes as a result of the upgrade. ### Resources - GHSA-j5gw-2vrg-8fgx is a similar PAX desynchronization bug - GHSA-fp55-jw48-c537 is another similar PAX desynchronization bug

Source published

29 May 2026 19:08:23 UTC

Source modified

29 May 2026 19:15:14 UTC

Observed here

24 Oct 2026 13:19:54 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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CVSS_V4 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N

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