UBUNTU-CVE-2026-55206
A vulnerability in the py7zr Python library prior to version 1.1.3 allows a crafted .7z archive to cause excessive CPU consumption due to an inefficient O(n^2) algorithm in PackInfo._read(). This can lead to denial of service by resource exhaustion during archive initialization. The issue is fixed in version 1.1.3.
AI Analysis
Technical Summary
The py7zr library, used for 7zip archive operations, contained an inefficient cumulative sum pattern in the PackInfo._read() function within archiveinfo.py. This pattern is O(n^2) in complexity and processes attacker-controlled numstreams values parsed from archive headers. An attacker can craft a malicious .7z archive that triggers excessive CPU usage during the SevenZipFile.init() call before extraction. This vulnerability was addressed and fixed in py7zr version 1.1.3.
Potential Impact
An attacker can cause excessive CPU consumption on systems processing malicious .7z archives with vulnerable py7zr versions, potentially leading to denial of service conditions due to resource exhaustion. There is no indication of code execution or data corruption from the provided data.
Mitigation Recommendations
Upgrade py7zr to version 1.1.3 or later, where the inefficient cumulative sum pattern in PackInfo._read() has been fixed. No other mitigation steps are indicated.
UBUNTU-CVE-2026-55206
Description
A vulnerability in the py7zr Python library prior to version 1.1.3 allows a crafted .7z archive to cause excessive CPU consumption due to an inefficient O(n^2) algorithm in PackInfo._read(). This can lead to denial of service by resource exhaustion during archive initialization. The issue is fixed in version 1.1.3.
CVSS v4.0
Affected software
pkg:deb/ubuntu/[email protected]+dfsg-4ubuntu0.1?arch=source&distro=jammypkg:deb/ubuntu/[email protected]+dfsg-8build1?arch=source&distro=noblepkg:deb/ubuntu/[email protected]+dfsg1-1?arch=source&distro=questingpkg:deb/ubuntu/[email protected]+dfsg-1?arch=source&distro=resoluteRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The py7zr library, used for 7zip archive operations, contained an inefficient cumulative sum pattern in the PackInfo._read() function within archiveinfo.py. This pattern is O(n^2) in complexity and processes attacker-controlled numstreams values parsed from archive headers. An attacker can craft a malicious .7z archive that triggers excessive CPU usage during the SevenZipFile.init() call before extraction. This vulnerability was addressed and fixed in py7zr version 1.1.3.
Potential Impact
An attacker can cause excessive CPU consumption on systems processing malicious .7z archives with vulnerable py7zr versions, potentially leading to denial of service conditions due to resource exhaustion. There is no indication of code execution or data corruption from the provided data.
Mitigation Recommendations
Upgrade py7zr to version 1.1.3 or later, where the inefficient cumulative sum pattern in PackInfo._read() has been fixed. No other mitigation steps are indicated.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- UBUNTU-CVE-2026-55206
- Osv Schema Version
- 1.7.0
- Aliases
- []
- Ecosystems
- ["Ubuntu:22.04:LTS","Ubuntu:24.04:LTS","Ubuntu:25.10","Ubuntu:26.04:LTS"]
- Database Specific Severity
- null
- Cvss Version
- 4.0
Threat ID: 6a58b47868715ace43d97fd4
Added to database: 07/16/2026, 10:37:44 UTC
Last enriched: 07/16/2026, 11:53:05 UTC
Last updated: 07/31/2026, 19:24:49 UTC
Views: 4
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