Heap corruption via shrunken shared scaffold buffer
Published Jun 19, 2026 · Updated Jun 19, 2026
Heap-based buffer overflow in Expat Project libexpat before 2.8.2 allows local users to corrupt memory via crafted XML. The doProlog function lets a shallow external parameter-entity subparser shrink the shared scaffIndex array to its private group size, so the resumed parent skips growth and writes beyond the heap allocation. Exploitation requires shared DTD state between the parent and subparser; successful triggering corrupts process memory, while reliable code execution has not been demonstrated.
Summary
What happened
Heap-based buffer overflow in Expat Project libexpat before 2.8.2 allows local users to corrupt memory via crafted XML. The doProlog function lets a shallow external parameter-entity subparser shrink the shared scaffIndex array to its private group size, so the resumed parent skips growth and writes beyond the heap allocation. Exploitation requires shared DTD state between the parent and subparser; successful triggering corrupts process memory, while reliable code execution has not been demonstrated.
The record
- CVE
- CVE-2026-56132
- Published
- Jun 19, 2026
- Updated
- Jun 19, 2026
- Vendor
- Expat Project
- Product
- libexpat
- Classifications
- CWE-821
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 19, 2026CVE publishedPublication date reported by the CVE source.
- Jun 19, 2026Record 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 <2.8.2
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
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Weakness, pattern, technique
Public exploit references
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Technologies
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Your stack
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