Service interruption via quadratic large-token reparsing
Published Feb 4, 2024 · Updated Nov 4, 2025
Resource-consumption flaw in Expat libexpat 2.5.0 and earlier allows remote attackers to interrupt services with crafted XML. During incremental parsing, the tokenizer reparses an incomplete large token from its start after each buffer fill, producing quadratic CPU work. Exposure requires an application to feed attacker-controlled XML across multiple XML_Parse or XML_ParseBuffer calls; one-shot parsing is unaffected.
Summary
What happened
Resource-consumption flaw in Expat libexpat 2.5.0 and earlier allows remote attackers to interrupt services with crafted XML. During incremental parsing, the tokenizer reparses an incomplete large token from its start after each buffer fill, producing quadratic CPU work. Exposure requires an application to feed attacker-controlled XML across multiple XML_Parse or XML_ParseBuffer calls; one-shot parsing is unaffected.
The record
- CVE
- CVE-2023-52425
- Published
- Feb 4, 2024
- Updated
- Nov 4, 2025
- Vendor
- Expat Project
- Product
- libexpat
- Classifications
- CWE-400, T1499.003
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Feb 4, 2024CVE publishedPublication date reported by the CVE source.
- Nov 4, 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?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <=2.5.0
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
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Technologies
Your stack
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Your stack
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