CVE-2026-107224
Received Received - Intake

Zip64 Size Overflow in Excelize Library

Publication date: 2026-10-07

Last updated on: 2026-10-07

Assigner: GitHub, Inc.

Description
Excelize is a Go language library for reading and writing Microsoft Excel spreadsheets. From 2.1.0 to 2.11.0, a Zip64 uncompressed size with the high bit set is converted from uint64 to a negative int64 before signed size-limit checks and allocation. ReadZipReader obtains UncompressedSize64 through FileInfo.Size and passes the wrapped negative value to readFile. When a crafted Zip64 entry declares an uncompressed size from 2^63 through 2^64-1 and the workbook is opened, the negative size bypasses unzip limits and reaches make as a negative capacity, allowing an attacker to panic during workbook opening. No fixed version is available as of this review.

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Meta Information

Published
2026-10-07
Last Modified
2026-10-07
Generated
2026-10-08
AI Q&A
2026-10-07
EPSS Evaluated
N/A
NVD
CVE-2026-107224
EUVD
EUVD-2026-94555

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
qax-os excelize >= 2.1.0, <= 2.11.0

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-190 The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.
CWE-681 When converting from one data type to another, such as long to integer, data can be omitted or translated in a way that produces unexpected values. If the resulting values are used in a sensitive context, then dangerous behaviors may occur.

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Executive Summary

This vulnerability affects the Excelize Go library for reading and writing Excel files. It occurs when a Zip64 uncompressed size exceeds the maximum value of a signed 64-bit integer (2^63), causing an integer overflow. The size is converted from uint64 to int64, becoming negative, which bypasses size limit checks. This negative value then triggers a panic in the make function due to an invalid capacity parameter.

Detection Guidance

This vulnerability is specific to applications using the excelize library versions 2.1.0 to 2.11.0. To detect it, check if your application depends on these versions by inspecting dependency files like go.mod or package-lock.json. No direct network detection commands are applicable as this is a library-level issue.

Impact Analysis

An attacker can craft a malicious Excel file with a Zip64 entry that has an uncompressed size between 2^63 and 2^64-1. When this file is opened using the vulnerable Excelize library, it causes a runtime panic, crashing the application. This can lead to denial-of-service conditions or application instability.

Compliance Impact

This vulnerability primarily impacts availability, causing crashes in applications using the Excelize library. While it does not directly expose data, repeated crashes could disrupt services handling sensitive information, potentially violating availability requirements in GDPR or HIPAA. However, no direct data exposure or confidentiality breach is described in the provided context.

Mitigation Strategies
  • Upgrade the excelize library to version 2.11.1 or later if your application uses it.
  • Review and update any custom code that processes ZIP archives to ensure proper size validation before decompression.
  • Apply input validation for ZIP files to reject files with Zip64 uncompressed sizes exceeding 2^63-1.

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