CVE-2026-55195 Details
Description
py7zr is a Python-based library and utility to support 7zip archive compression, decompression, encryption and decryption. Prior to 1.1.3, py7zr's Worker.decompress() extracted archive entries without tracking total decompressed size, allowing a crafted .7z file such as a 15.6 KB archive that expands to 100 MB to exhaust disk or memory before extraction completes. This issue is fixed in version 1.1.3.
A denial-of-service vulnerability has been identified in the py7zr library, which is used for handling 7zip archives in Python. In versions prior to 1.1.3, the library's decompression function did not monitor the total size of extracted data. This oversight allowed a specially crafted .7z file to cause significant resource exhaustion, such as a 15.6 KB archive expanding to 100 MB, before the extraction process was completed. The issue arises because the decompression function writes data directly to disk without any size limitations or tracking, creating a 'decompression bomb' effect that can overwhelm system resources.
Users can upgrade to py7zr version 1.1.3 or later, where this vulnerability has been fixed. The latest version can be downloaded from the Python Package Index (PyPI).
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Jul 8, 2026CISA-ADP
Assessed Jul 9, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/miurahr/py7zr/security/advisories/GHSA-gjrg-mpp7-g774 | CISA-ADP | AdvisoryExploitRemedyVendor |
| https://github.com/miurahr/py7zr/commit/28faf107b64374fa5a02bfb93aa2024e281ca97b | [email protected] | Source CodeVendor |
| https://github.com/miurahr/py7zr/releases/tag/v1.1.3 | [email protected] | Release NotesVendor |
| https://github.com/miurahr/py7zr/security/advisories/GHSA-gjrg-mpp7-g774 | [email protected] | AdvisoryExploitRemedyVendor |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-409 | Improper Handling of Highly Compressed Data (Data Amplification) | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| py7zr | <= 1.1.2 (semver) |
CPE
Remediation
| |
Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 9, 2026 | CVE Modified | CISA-ADP |
| Jul 8, 2026 | New CVE Received | [email protected] |