CVE-2021-41253

Summary

CVECVE-2021-41253
StatePUBLIC
Assigner[email protected]
Source PriorityCVE Program / NVD first with legacy fallback
Published2021-11-08 22:15:00 UTC
Updated2022-10-24 16:07:00 UTC
DescriptionZydis 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.

Risk And Classification

Problem Types: CWE-908

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Zyantific Zydis All All All All

References

ReferenceSourceLinkTags
huntr: Disclose & Fix Security Vulnerabilities in Open Source MISC huntr.dev
Possible heap buffer overflow when using zycore string functions in formatter hooks · Advisory · zyantific/zydis · GitHub CONFIRM github.com
huntr: Disclose & Fix Security Vulnerabilities in Open Source MISC huntr.dev
Fix struct initialization in formatter · zyantific/zydis@55dd08c · GitHub MISC github.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Legacy QID Mappings

  • 184630 Debian Security Update for zydis (CVE-2021-41253)
  • 690953 Free Berkeley Software Distribution (FreeBSD) Security Update for zydis (d487d4fc-43a8-11ed-8b01-b42e991fc52e)

© CVE.report 2026

Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties, implied or otherwise, with regard to this information or its use. Any use of this information is at the user's risk. It is the responsibility of user to evaluate the accuracy, completeness or usefulness of any information, opinion, advice or other content. EACH USER WILL BE SOLELY RESPONSIBLE FOR ANY consequences of his or her direct or indirect use of this web site. ALL WARRANTIES OF ANY KIND ARE EXPRESSLY DISCLAIMED. This site will NOT BE LIABLE FOR ANY DIRECT, INDIRECT or any other kind of loss.

CVE, CWE, and OVAL are registred trademarks of The MITRE Corporation and the authoritative source of CVE content is MITRE's CVE web site. This site includes MITRE data granted under the following license.

Free CVE JSON API cve.report/api

CVE.report and Source URL Uptime Status status.cve.report