Description
py7zr is a Python-based library and utility to support 7zip archive compression, decompression, encryption and decryption. Prior to 1.1.3, PackInfo._read() in archiveinfo.py used an O(n^2) cumulative sum pattern for attacker-controlled numstreams values parsed from archive headers, allowing a crafted .7z archive to cause excessive CPU consumption during SevenZipFile.init() before extraction. This issue is fixed in version 1.1.3.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| miurahr | py7zr | < 1.1.3 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | py7zr | 1.1.3+dfsg-1 | — |
| Debian 13 | py7zr | No fix yet | — |
| Debian 12 | py7zr | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | py7zr | No fix yet | — |
| Ubuntu 26.04 LTS | py7zr | No fix yet | — |
| Ubuntu 25.10 | py7zr | No fix yet | — |
| Ubuntu 24.04 LTS | py7zr | No fix yet | — |
| Ubuntu 22.04 LTS | py7zr | No fix yet | — |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | python-py7zr | 1.1.3-1.1 | openSUSE-SU-2026:11112-1 |
| openSUSE Leap 16.0 | python-py7zr | 1.0.0-bp160.2.1 | openSUSE-SU-2026:21159-1 |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| PyPI | py7zr | < 1.1.3 | 1.1.3 | GHSA-h4gh-22qq-72r7 |
Advisories 2
- openSUSE-SU-2026:21159-1 Security update for python-py7zr SUSE / openSUSE Security Updates · Jun 30, 2026
- openSUSE-SU-2026:11112-1 python311-py7zr-1.1.3-1.1 on GA media SUSE / openSUSE Security Updates · Jun 24, 2026