CVE-2026-55195 miurahr CVE debrief

Who should care

Users of py7zr library, especially those who handle 7zip archives on Linux, Windows, or macOS platforms, and security teams responsible for vulnerability management, should be aware of this vulnerability and take steps to mitigate it by upgrading to version 1.1.3 or later. This includes operators managing affected deployments and teams overseeing security posture.

Technical summary

The py7zr library did not track the total decompressed size of archive entries during decompression, allowing a crafted 7z file to cause a denial of service by exhausting system resources such as disk space or memory. This issue was addressed by adding size tracking in version 1.1.3, which prevents archive entries from expanding beyond the available resources. Affected deployments should prioritize upgrading to the patched version to mitigate potential denial of service attacks.

Defensive priority

High, immediate attention recommended due to potential for denial of service through crafted 7z files. Upgrade py7zr to version 1.1.3 or later, validate and sanitize 7zip archives before processing, and monitor system resources during archive decompression to mitigate this vulnerability effectively. Consider compensating controls for exposed systems while remediation is scheduled and verified. Track exceptions, retest remediated assets, and close the item only after evidence is documented. Review relevant monitoring, detection, and logs for exposed assets that need extra review. Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up. Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed. Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance. Check asset inventory for potential exposure and implement source tracking for affected systems. Implement monitoring to detect potential exploitation attempts. Consider rollback/change windows for remediation if necessary. Review compensating controls for exposed systems while remediation is scheduled and verified. Track exceptions, retest remediated assets, and close the item only after evidence is documented. Review relevant monitoring, detection, and logs for exposed assets that need extra review. Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up. Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed. Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance. Check asset inventory for potential exposure and implement source tracking for affected systems. Implement monitoring to detect potential exploitation attempts. Consider rollback/change windows for remediation if necessary. Implement compensating controls for exposed systems while remediation is scheduled and verified. Track exceptions, retest remediated assets, and close the item only after evidence is documented. Review relevant monitoring, detection,

Recommended defensive actions

• Upgrade py7zr to version 1.1.3 or later
• Validate and sanitize 7zip archives before processing
• Monitor system resources during archive decompression
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance
• Check asset inventory for potential exposure and implement source tracking for affected systems
• Implement monitoring to detect potential exploitation attempts

Evidence notes

The CVE record was published on 2026-07-08T21:16:49.840Z and last modified on 2026-07-10T19:06:45.623Z. The NVD entry is currently Deferred. Evidence is limited to CVE and NVD details. Defenders should verify affected py7zr library deployments and review official advisories for scope and guidance.

Official resources