zip: AES Entry HMAC Authentication Bypass on Premature EOF

zip is a zip library for Rust that supports reading and writing simple ZIP files. From 0.6.0 until 9.0.0, the AES entry reader in src/aes.rs verifies its HMAC only when the attacker-controlled data counter reaches zero. If the underlying bounded reader reaches the real end of the archive while data_remaining is still positive, or if an encrypted entry has no payload, the reader can return a clean end of stream without reading and comparing the authentication tag. Applications using by_index_decrypt, by_name_decrypt, by_path_decrypt, or password-enabled by_index_with_options can therefore accept modified plaintext without an authentication error. This issue is fixed in version 9.0.0.

Source published

26 Oct 2026 16:30:30 UTC

Source modified

26 Oct 2026 16:30:30 UTC

Observed here

26 Oct 2026 17:35:31 UTC

Source terms

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CVSS 3.1 · 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N