pyzipper is a replacement for Python's zipfile that can read and write AES encrypted zip files. Prior to 0.4.0, a Python operator precedence bug in pyzipper/zipfile_aes.py caused the AE-2 format to never be automatically selected during encryption, causing encrypted entries to be written in AE-1 format and exposing the plaintext CRC32 checksum in the ZIP header and, for unseekable zip archives, in the datadescripter section, allowing an attacker who possesses the archive to brute-force candidate plaintexts for small or low-entropy files by comparing CRC32 values. This issue is fixed in version 0.4.0.

Project Subscriptions

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-crqm-m339-7m2p pyzipper has an encryption bypass for small files encrypted using it
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Fri, 17 Jul 2026 18:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Fri, 17 Jul 2026 16:45:00 +0000

Type Values Removed Values Added
Description pyzipper is a replacement for Python's zipfile that can read and write AES encrypted zip files. Prior to 0.4.0, a Python operator precedence bug in pyzipper/zipfile_aes.py caused the AE-2 format to never be automatically selected during encryption, causing encrypted entries to be written in AE-1 format and exposing the plaintext CRC32 checksum in the ZIP header and, for unseekable zip archives, in the datadescripter section, allowing an attacker who possesses the archive to brute-force candidate plaintexts for small or low-entropy files by comparing CRC32 values. This issue is fixed in version 0.4.0.
Title pyzipper: Encryption bypass for small files encrypted with pyzipper
Weaknesses CWE-480
References
Metrics cvssV3_1

{'score': 6.2, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-07-17T17:25:08.270Z

Reserved: 2026-05-07T18:04:17.308Z

Link: CVE-2026-44722

cve-icon Vulnrichment

Updated: 2026-07-17T17:25:04.389Z

cve-icon NVD

No data.

cve-icon Redhat

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cve-icon OpenCVE Enrichment

No data.

Weaknesses