zchunk up to 1.5.4 Header Parsing src/lib/header.c read_preface out-of-bounds

Summaryinfo

A vulnerability described as problematic has been identified in zchunk up to 1.5.4. Affected by this issue is the function read_preface of the file src/lib/header.c of the component Header Parsing. Such manipulation leads to out-of-bounds. This vulnerability is listed as CVE-2026-117556. The attack may be performed from remote. There is no available exploit. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability was found in zchunk up to 1.5.4 and classified as problematic. Affected by this issue is the function read_preface of the file src/lib/header.c of the component Header Parsing. The manipulation with an unknown input leads to a out-of-bounds vulnerability. Using CWE to declare the problem leads to CWE-125. The product reads data past the end, or before the beginning, of the intended buffer. Impacted is availability. CVE summarizes:

zchunk before 1.5.5 contains a heap out-of-bounds read vulnerability in read_preface() 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.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-117556 since 10/27/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Successful exploitation requires user interaction by the victim. There are known technical details, but no exploit is available.

Upgrading to version 1.5.5 eliminates this vulnerability.

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Productinfo

Name

• zchunk

Version

• 1.5.0
• 1.5.1
• 1.5.2
• 1.5.3
• 1.5.4

Website

• Product: https://github.com/zchunk/zchunk/

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