CVE-2021-33928: 
NixOS vulnerability analysis and mitigation

A buffer overflow vulnerability was identified in libsolv before version 0.7.17, specifically affecting the pool_installable function in src/repo.h. This vulnerability was assigned CVE-2021-33928 and was discovered in June 2021 (NVD, CVE).

The vulnerability exists in the pool_installable function within src/repo.h of libsolv. The issue occurs when the index value 'id>>3' becomes larger than pool->considered->size, leading to a heap buffer overflow condition. The vulnerability stems from improper bounds checking in the MAPTST macro, defined as ((m)->map[(n) >> 3] & (1 << ((n) & 7))) (Github Issue).

When exploited, this vulnerability allows attackers to cause a Denial of Service condition in affected systems (NVD).

The vulnerability can be triggered through specially crafted input that causes the index value to exceed the allocated buffer size. A proof of concept exploit has been documented that demonstrates the heap buffer overflow condition (Github Issue).

The vulnerability has been addressed in libsolv version 0.7.17 and later. Users are advised to upgrade to this version or later. Red Hat has released security updates for affected versions in their Enterprise Linux distributions (Red Hat).