CVE-2026-56403
CSIRTS triage
- What
- The vulnerability is an integer overflow in the storeAtts function.
- Who is affected
- Deployments using libexpat versions before 2.8.2.
- Urgency
- Remediation is medium urgency due to the medium severity rating.
- Action
- Upgrade to libexpat version 2.8.2 or later.
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Exploitation outlook
- Low exploitation risk0.10% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 1% of all EPSS-scored CVEs.
Advisory coverage (1)
- mediumCVE-2026-56403: libexpat before 2.8.2 has an integer overflow in storeAtts.msrc · 2026-06-09
External references
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[](https://www.csirts.com/cve/CVE-2026-56403)