Memory corruption via reentrant parser handler calls
Published Jun 4, 2026 · Updated Jun 4, 2026
Use-after-free in Expat Project libexpat before 2.8.2 allows local users to corrupt process memory through reentrant handler calls. The parser fails to track handler-call depth, so a callback can free or reset its active parser, or reenter parsing and buffer APIs, while outer parsing code still uses parser storage. Reachability requires an embedding application or language binding to expose reentrant handler behavior; corruption is confined to that hosting process.
Summary
What happened
Use-after-free in Expat Project libexpat before 2.8.2 allows local users to corrupt process memory through reentrant handler calls. The parser fails to track handler-call depth, so a callback can free or reset its active parser, or reenter parsing and buffer APIs, while outer parsing code still uses parser storage. Reachability requires an embedding application or language binding to expose reentrant handler behavior; corruption is confined to that hosting process.
The record
- CVE
- CVE-2026-50219
- Published
- Jun 4, 2026
- Updated
- Jun 4, 2026
- Vendor
- Expat Project
- Product
- libexpat
- Classifications
- CWE-416
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 4, 2026CVE publishedPublication date reported by the CVE source.
- Jun 4, 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
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What is affected?
Published CVSS scores
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