CVE-2021-28651: Debian Linux

High severity, CVSS 7.5. EPSS: 7.5% chance of exploitation in the next 30 days.

An issue was discovered in Squid before 4.15 and 5.x before 5.0.6. Due to a buffer-management bug, it allows a denial of service. When resolving a request with the urn: scheme, the parser leaks a small amount of memory. However, there is an unspecified attack methodology that can easily trigger a large amount of memory consumption.

Affected products

• Debian Debian Linux: version 9.0 only; version 10.0 only
• Fedoraproject Fedora: version 33 only; version 34 only
• Netapp Cloud Manager: affected versions not specified
• Squid-Cache Squid: from 2.0, before 4.15 (fixed in 4.15); from 5.0, before 5.0.6 (fixed in 5.0.6)

Published 2021-05-27. Last modified 2026-06-17.