CVE-2021-41253

 

Published at: - 08-11-2021 11:15

Last modified: - 24-10-2022 06:07

Total changes: - 2

Description

Zydis is an x86/x86-64 disassembler library. Users of Zydis versions v3.2.0 and older that use the string functions provided in `zycore` in order to append untrusted user data to the formatter buffer within their custom formatter hooks can run into heap buffer overflows. Older versions of Zydis failed to properly initialize the string object within the formatter buffer, forgetting to initialize a few fields, leaving their value to chance. This could then in turn cause zycore functions like `ZyanStringAppend` to make incorrect calculations for the new target size, resulting in heap memory corruption. This does not affect the regular uncustomized Zydis formatter, because Zydis internally doesn't use the string functions in zycore that act upon these fields. However, because the zycore string functions are the intended way to work with the formatter buffer for users of the library that wish to extend the formatter, we still consider this to be a vulnerability in Zydis. This bug is patched starting in version 3.2.1. As a workaround, users may refrain from using zycore string functions in their formatter hooks until updating to a patched version.

Common Vulnerability Scoring System (CVSS)

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

 

Verification logic

 

Reference

• https://huntr.dev/bounties/96b0a482-7041-45b1-9327-c6a4a8f32d3a
• https://github.com/zyantific/zydis/commit/55dd08c210722aed81b38132f5fd4a04ec1943b5
• https://huntr.dev/bounties/d2536d7d-36ce-4723-928c-98d1ee039784
• https://github.com/zyantific/zydis/security/advisories/GHSA-q42v-hv86-3m4g

 

Keywords

NVD

 

CVE-2021-41253

 

CVE

 

Common vulnerabilities & exposures

 

CVSS

 

Common vulnerability scoring system

 

Security

 

Vulnerabilities

 

Exposures