Code execution via signed RAR copy length
Published Jan 9, 2024 · Updated Nov 3, 2025
Heap-based buffer overflow in Microsoft Windows libarchive allows local users to execute code by opening a crafted RAR archive. The RAR4 copy_from_lzss_window_to_unp routine accepts a signed length that can become negative and then converts it into a huge memcpy size without bounding it to the destination buffer. Exploitation requires a local low-privileged user to process the archive, and successful exploitation runs code in that user's context.
Summary
What happened
Heap-based buffer overflow in Microsoft Windows libarchive allows local users to execute code by opening a crafted RAR archive. The RAR4 copy_from_lzss_window_to_unp routine accepts a signed length that can become negative and then converts it into a huge memcpy size without bounding it to the destination buffer. Exploitation requires a local low-privileged user to process the archive, and successful exploitation runs code in that user's context.
The record
- CVE
- CVE-2024-20696
- Published
- Jan 9, 2024
- Updated
- Nov 3, 2025
- Vendor
- Microsoft
- Product
- Windows Server 2019
- Classifications
- CWE-122, T1203
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Jan 9, 2024CVE publishedPublication date reported by the CVE source.
- Nov 3, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=10.0.17763.0 <10.0.17763.5329
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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