Memory corruption via untracked CDATA handler reentry
Published Jun 21, 2026 · Updated Jun 21, 2026
Use-after-free in Expat Project libexpat before 2.8.2 allows local users to corrupt parser memory via CDATA handler reentry. The doCdataSection function invokes m_characterDataHandler for XML_TOK_DATA_CHARS without bracketing the call with beforeHandler and afterHandler, leaving handler depth at zero. Exploitation requires handler reentry during a policy violation and can expose, modify, or crash the parsing process.
Summary
What happened
Use-after-free in Expat Project libexpat before 2.8.2 allows local users to corrupt parser memory via CDATA handler reentry. The doCdataSection function invokes m_characterDataHandler for XML_TOK_DATA_CHARS without bracketing the call with beforeHandler and afterHandler, leaving handler depth at zero. Exploitation requires handler reentry during a policy violation and can expose, modify, or crash the parsing process.
The record
- CVE
- CVE-2026-56412
- Published
- Jun 21, 2026
- Updated
- Jun 21, 2026
- Vendor
- Expat Project
- Product
- libexpat
- Classifications
- CWE-416
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 21, 2026CVE publishedPublication date reported by the CVE source.
- Jun 21, 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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Public exploit references
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