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

Affected Software

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.

References

• https://bugs.squid-cache.org/show_bug.cgi?id=5104
• https://github.com/squid-cache/squid/security/advisories/GHSA-ch36-9jhx-phm4
• https://www.debian.org/security/2021/dsa-4924
• https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/T4EPIWUZDJAXADDHVOPKRBTQHPBR6H66/
• https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/LSQ3U54ZCNXR44QRPW3AV2VCS6K3TKCF/
• https://lists.debian.org/debian-lts-announce/2021/06/msg00014.html
• https://security.netapp.com/advisory/ntap-20210716-0007/