CVE-2026-117556: zchunk before 1.5.5 Heap Out-of-Bounds Read via read_preface()
zchunk before 1.5.5 contains a heap out-of-bounds read vulnerability in readpreface() in src/lib/header.c that passes the total header length instead of remaining bytes to compint parsing functions. Attackers can supply a crafted .zck file whose header ends inside a compressed integer, causing reads past the heap header buffer and crashing the application.
Affected Software
Event History
Frequently Asked Questions
What must an attacker provide to trigger the issue?
An attacker must cause the application to process a crafted .zck file with a header that ends in the middle of a compressed integer. The vulnerability is triggered while read_preface() parses that header.
What is the practical impact of successful exploitation?
The described impact is an out-of-bounds read past the heap-allocated header buffer, which can crash the application. The provided data does not indicate confidentiality or integrity impact.
Which versions need remediation?
zchunk versions before 1.5.5 are affected. Updating to 1.5.5 or later addresses the affected version range.