Affected: astral-sh uv

uv is a Python package and project manager written in Rust. In versions 0.8.5 and earlier, remote ZIP archives were handled in a streamwise fashion, and file entries were not reconciled against the archive's central directory. An attacker could contrive a ZIP archive that would extract with legitimate contents on some package installers, and malicious contents on others due to multiple local file entries. An attacker could also contrive a "stacked" ZIP input with multiple internal ZIPs, which would be handled differently by different package installers. The attacker could choose which installer to target in both scenarios. This issue is fixed in version 0.8.6. To work around this issue, users may choose to set UV_INSECURE_NO_ZIP_VALIDATION=1 to revert to the previous behavior.

Affected: PyPI: uv

## Impact

In versions 0.8.5 and earlier of uv, remote ZIP archives were handled in a streamwise fashion, and file entries were not reconciled against the archive's central directory. This enabled two parser differentials against other Python package installers:

1. An attacker could contrive a ZIP archive that would extract with legitimate contents on some package installers, and malicious contents on others due to multiple local file entries. The attacker could choose which installer to target. 2. An attacker could contrive a "stacked" ZIP input with multiple internal ZIPs, which would be handled differently by different package installers. The attacker could choose which installer to target.

In both cases, the outcome is that an attacker can produce a ZIP with a consistent digest that expands differently with different installers.

The [ZIP standard](https://pkware.cachefly.net/webdocs/casestudies/APPNOTE.TXT) is ambiguous with respect to these behavior differentials. Consequently, these same differentials may be accepted ZIP parsers other than those used in uv. This advisory is for uv in particular, but all consumers of ZIP-based Python package distributions, e.g., pip, are potentially susceptible to similar parser differentials in other ZIP parsers.

The practical impact of these differentials is limited by a number of factors:

- To be compromised via this vulnerability, user interaction of some sort is required. In particular, the user must run `uv install $package`…