USN-8813-1: Expat vulnerabilities
Ubuntu's USN-8813-1 patches Expat flaws that can crash the parser or allow code execution.
Ubuntu published USN-8813-1 for vulnerabilities in the Expat XML parser. Integer-arithmetic issues (CVE-2026-56406, CVE-2026-56407, CVE-2026-56409, CVE-2026-56410, CVE-2026-56411) could let an attacker cause a denial of service. Separate flaws in handler-call-depth tracking (CVE-2026-56131) and memory handling (CVE-2026-56132) could crash Expat or lead to arbitrary code execution. The notice also describes incorrect Unicode handling; it does not report active exploitation.
- USN-8813-1 covers multiple Expat flaws in Ubuntu packages.
- Integer-arithmetic bugs may allow denial of service.
- Handler-depth and memory bugs may crash Expat or allow code execution.
- No exploitation in the wild is reported in the notice.
Vulnerabilities mentioned
All| CVE | Vulnerability | CVSS | EPSS | Signals | Published |
|---|---|---|---|---|---|
CVE-2026-56132+1 related CVE | In libexpat before 2.8.2, there is a heap-based buffer overflow in doProlog in xmlparse.c because scaffold backing array reallocation is mishandled when there… | 6.9 group max | <1% | ||
CVE-2026-56406+4 related CVEs | libexpat before 2.8.2 has an integer overflow in XML_ParseBuffer because it lacked a check that was present in XML_Parse | 6.9 group max | <1% |
From the original article
It was discovered that Expat did not correctly handle certain integer arithmetic. An attacker could possibly use this issue to cause a denial of service. (CVE-2026-56406, CVE-2026-56407, CVE-2026-56409, CVE-2026-56410, CVE-2026-56411) It was discovered that Expat did not correctly track handler call depth.
ubuntu.com
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