CVE-2026-6040
Deferred Deferred - Pending Action

Heap Use-After-Free in LibreOffice ODF Number Format Handling

Vulnerability report for CVE-2026-6040, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.

Publication date: 2026-06-15

Last updated on: 2026-06-30

Assigner: Document Foundation, The

Description

A heap use-after-free existed when importing the blank-width characters of an ODF number format. A position value read from the document was not checked against the length of the format-code string, so a malformed number format could be processed against memory outside that string. In fixed versions the position is bounds-checked before use.

CVSS Scores

EPSS Scores

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Meta Information

Published
2026-06-15
Last Modified
2026-06-30
Generated
2026-07-06
AI Q&A
2026-06-15
EPSS Evaluated
2026-07-04
NVD
EUVD

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
documentfoundation libreoffice *

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-825 The product dereferences a pointer that contains a location for memory that was previously valid, but is no longer valid.
CWE-416 The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.
CWE-787 The product writes data past the end, or before the beginning, of the intended buffer.

Attack-Flow Graph

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Executive Summary

This vulnerability is a heap use-after-free issue that occurs when importing blank-width characters in an ODF number format. Specifically, a position value read from the document was not properly checked against the length of the format-code string. As a result, a malformed number format could cause the program to access memory outside the intended string, leading to potential memory corruption. The issue has been fixed by adding bounds checking on the position value before it is used.

Impact Analysis

This vulnerability can lead to memory corruption due to accessing memory outside the intended bounds. Such memory corruption can cause crashes, unexpected behavior, or potentially allow an attacker to execute arbitrary code or escalate privileges. The CVSS score of 5.4 indicates a moderate severity with local attack vector and low complexity, requiring user interaction.

Mitigation Strategies

To mitigate this vulnerability, ensure that you update to a fixed version of the affected software where the position value is bounds-checked before use.

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