Application crash or heap disclosure via uninitialized MSAT
Published Jun 3, 2026 · Updated Jun 3, 2026
Use of uninitialized memory in libxls 1.6.3 and earlier allows attackers to crash applications or disclose heap residue via crafted XLS files. In read_MSAT(), the parser leaves part of the heap-allocated Master Sector Allocation Table uninitialized, then ole2_validate_sector_chain() reads it. Exploitation requires an application to parse an attacker-controlled XLS file; the bounded outcomes are an application crash or disclosure of residual heap data.
Summary
What happened
Use of uninitialized memory in libxls 1.6.3 and earlier allows attackers to crash applications or disclose heap residue via crafted XLS files. In read_MSAT(), the parser leaves part of the heap-allocated Master Sector Allocation Table uninitialized, then ole2_validate_sector_chain() reads it. Exploitation requires an application to parse an attacker-controlled XLS file; the bounded outcomes are an application crash or disclosure of residual heap data.
The record
- CVE
- CVE-2026-26824
- Published
- Jun 3, 2026
- Updated
- Jun 3, 2026
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-457
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 3, 2026CVE publishedPublication date reported by the CVE source.
- Jun 3, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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What is affected?
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Published CVSS scores
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Attacks
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Weakness, pattern, technique
Public exploit references
- Crafted XLS reproducer for libxls issue 155proof of concept · demonstrated
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Technologies
Your stack
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Your stack
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