CVE-2021-41253: 
NixOS vulnerability analysis and mitigation

Zydis, an x86/x64 disassembler library, versions prior to 3.2.1 contain a vulnerability where improper initialization of string objects within the formatter buffer could lead to heap buffer overflows. The vulnerability (CVE-2021-41253) was discovered and disclosed on November 8, 2021. The issue affects users who utilize the string functions provided in zycore to append untrusted user data to the formatter buffer within custom formatter hooks (GitHub Advisory).

The vulnerability stems from incomplete initialization of string objects within the formatter buffer, where certain fields were left uninitialized. This could cause functions like ZyanStringAppend to perform incorrect calculations for new target sizes, potentially resulting in heap memory corruption. The regular uncustomized Zydis formatter is not affected as it doesn't internally use the zycore string functions that depend on these fields (GitHub Advisory).

When exploited, this vulnerability could lead to heap buffer overflows when processing untrusted user data through custom formatter hooks. This could potentially result in memory corruption and system instability. The impact is limited to users who specifically implement custom formatter hooks using zycore string functions (GitHub Advisory).

The vulnerability has been patched in version 3.2.1. Users are advised to upgrade to this version or later. For those unable to update immediately, the recommended workaround is to refrain from using zycore string functions in formatter hooks until updating to a patched version (GitHub Advisory).