CVE-2026-117556
Received Received - Intake

Heap Out-of-Bounds Read in zchunk Before 1.5.5

Publication date: 2026-10-27

Last updated on: 2026-10-27

Assigner: VulnCheck

Description
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.

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Meta Information

Published
2026-10-27
Last Modified
2026-10-27
Generated
2026-10-27
AI Q&A
2026-10-27
EPSS Evaluated
N/A
NVD
CVE-2026-117556
EUVD
EUVD-2026-110834

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
zchunk zchunk 0

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-125 The product reads data past the end, or before the beginning, of the intended buffer.

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Executive Summary

zchunk before 1.5.5 has a heap out-of-bounds read flaw in the read_preface() function. The issue occurs when the total header length is incorrectly passed to compressed integer parsing functions instead of the remaining bytes. This causes the application to read past the heap header buffer when processing a crafted .zck file with a header ending inside a compressed integer, leading to crashes.

Detection Guidance

This vulnerability can be detected by checking the installed version of zchunk. Run 'zchunk --version' to verify if the version is below 1.5.5. Additionally, inspect any .zck files processed by zchunk for malformed headers or crashes during decompression.

Impact Analysis

This vulnerability could allow attackers to crash the application by providing a maliciously crafted .zck file. If you process such files, it may lead to denial-of-service conditions, disrupting services that rely on zchunk for compression.

Mitigation Strategies

Immediately update zchunk to version 1.5.5 or later. Avoid processing untrusted .zck files until the update is applied. Monitor applications using zchunk for crashes or unexpected behavior.

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