CVE-2026-55195CWE-409

py7zr: Decompression bomb (zip bomb) denial of service via unchecked extraction size

High · published July 8, 2026

CVSS v4.0
8.7
EPSS
0%
Percentile
23.9
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v4.0
8.7 · HIGH
Vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
EPSS
0.00321 · 23.9th percentile
Weakness
CWE-409 · Improper Handling of Highly Compressed Data (Data Amplification)
Published
2026-07-08T20:30Z
EPSS history
Timeline
  • 08 JUL 20:30Z
    py7zr: Decompression bomb (zip bomb) denial of service via unchecked extraction size
    cvelistv5