Heap corruption via block length integer overflow
Published Jul 4, 2025 · Updated Jul 8, 2025
Heap-based buffer overflow in Jed Wing CHMLib through commit 2bef8d0 allows local users to crash a consuming process via a crafted CHM file. The reset-table parser accepts block lengths up to UINT_MAX, but _chm_decompress_block adds 6,144 using narrower arithmetic, allocates an undersized buffer, and _chm_fetch_bytes overwrites the heap. Exploitation requires a consuming application to process the crafted file; published evidence demonstrates memory corruption and a crash, not code execution.
Summary
What happened
Heap-based buffer overflow in Jed Wing CHMLib through commit 2bef8d0 allows local users to crash a consuming process via a crafted CHM file. The reset-table parser accepts block lengths up to UINT_MAX, but _chm_decompress_block adds 6,144 using narrower arithmetic, allocates an undersized buffer, and _chm_fetch_bytes overwrites the heap. Exploitation requires a consuming application to process the crafted file; published evidence demonstrates memory corruption and a crash, not code execution.
The record
- CVE
- CVE-2025-48172
- Published
- Jul 4, 2025
- Updated
- Jul 8, 2025
- Vendor
- Jed Wing
- Product
- CHMLib
- Classifications
- CWE-190, T1499.004
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 4, 2025CVE publishedPublication date reported by the CVE source.
- Jul 8, 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=0 <=2bef8d063ec7d88a8de6fd9f0513ea42ac0fa21f
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
- Crafted CHM proof-of-concept fileproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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