CVE-2021-28651

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.

Weakness

The product does not sufficiently track and release allocated memory after it has been used, which slowly consumes remaining memory.

Affected Software

Name	Vendor	Start Version	End Version
Squid	Squid-cache	2.0 (including)	4.15 (excluding)
Squid	Squid-cache	5.0 (including)	5.0.6 (excluding)
Red Hat Enterprise Linux 8	RedHat	squid:4-8050020210618131503.b4937e53	*
Squid	Ubuntu	devel	*
Squid	Ubuntu	focal	*
Squid	Ubuntu	groovy	*
Squid	Ubuntu	hirsute	*
Squid	Ubuntu	impish	*
Squid	Ubuntu	jammy	*
Squid	Ubuntu	kinetic	*
Squid	Ubuntu	lunar	*
Squid	Ubuntu	mantic	*
Squid	Ubuntu	noble	*
Squid	Ubuntu	trusty	*
Squid	Ubuntu	upstream	*
Squid3	Ubuntu	bionic	*
Squid3	Ubuntu	esm-infra/xenial	*
Squid3	Ubuntu	trusty	*
Squid3	Ubuntu	xenial	*

Potential Mitigations

Choose a language or tool that provides automatic memory management, or makes manual memory management less error-prone.
For example, glibc in Linux provides protection against free of invalid pointers.
When using Xcode to target OS X or iOS, enable automatic reference counting (ARC) [REF-391].
To help correctly and consistently manage memory when programming in C++, consider using a smart pointer class such as std::auto_ptr (defined by ISO/IEC ISO/IEC 14882:2003), std::shared_ptr and std::unique_ptr (specified by an upcoming revision of the C++ standard, informally referred to as C++ 1x), or equivalent solutions such as Boost.

NVD	https://nvd.nist.gov/vuln/detail/CVE-2021-28651
CWE	https://cwe.mitre.org/data/definitions/401.html

Missing Release of Memory after Effective Lifetime

Weakness

Affected Software

Potential Mitigations

References