Memory corruption via reentrant parser resume
Published Jun 19, 2026 · Updated Jun 19, 2026
Use-after-free in Expat Project libexpat before 2.8.2 allows local users to corrupt memory by re-entering a suspended XML parser. XML_ResumeParser omits the handler-depth guard and invokes callProcessor while the outer handler remains on the stack, permitting freed parser state to be reused. Reachability requires an embedding application whose handler suspends and resumes parsing during a policy violation; successful triggering can disclose memory, corrupt data, or crash the process.
Summary
What happened
Use-after-free in Expat Project libexpat before 2.8.2 allows local users to corrupt memory by re-entering a suspended XML parser. XML_ResumeParser omits the handler-depth guard and invokes callProcessor while the outer handler remains on the stack, permitting freed parser state to be reused. Reachability requires an embedding application whose handler suspends and resumes parsing during a policy violation; successful triggering can disclose memory, corrupt data, or crash the process.
The record
- CVE
- CVE-2026-56131
- Published
- Jun 19, 2026
- Updated
- Jun 19, 2026
- Vendor
- Expat Project
- Product
- libexpat
- Classifications
- CWE-416
- 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
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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?
Attacks
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