Application crash via truncated QName length arithmetic
Published Jun 12, 2025 · Updated Sep 1, 2026
Stack buffer overflow in XMLSoft libxml2 before 2.14.4 allows remote attackers to crash applications via crafted XML input. xmlBuildQName casts size_t prefix and local-name lengths to int before calculating the QName buffer size, then memcpy uses the wrapped result and writes beyond the stack buffer. Exploitation requires an application to pass attacker-influenced XML-derived name components to this function; the published impact is a service-interrupting crash.
Summary
What happened
Stack buffer overflow in XMLSoft libxml2 before 2.14.4 allows remote attackers to crash applications via crafted XML input. xmlBuildQName casts size_t prefix and local-name lengths to int before calculating the QName buffer size, then memcpy uses the wrapped result and writes beyond the stack buffer. Exploitation requires an application to pass attacker-influenced XML-derived name components to this function; the published impact is a service-interrupting crash.
The record
- CVE
- CVE-2025-6021
- Published
- Jun 12, 2025
- Updated
- Sep 1, 2026
- Vendor
- XMLSoft
- Product
- libxml2
- Classifications
- CWE-787, T1499
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 12, 2025CVE publishedPublication date reported by the CVE source.
- Sep 1, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <2.14.4
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
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
- GNOME libxml2 issue 926 reproducerproof of concept · unverified
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo