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CVE-2026-66046 is a denial-of-service vulnerability in Expat through version 2.8.3. The storeAtts() function in xmlparse.c performs a linear scan of elementType->defaultAtts to determine CDATA status for each specified attribute with a non-normalized value. Processing N such attributes therefore has O(N²) complexity. A moderately sized, well-formed XML document can trigger disproportionate CPU consumption in applications that parse untrusted XML.
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What an attacker gets, and what they’ve been doing with it.
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Patch, then assume compromise.
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No public exploit code observed for this vulnerability.
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
16 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A remote unauthenticated denial-of-service vulnerability in Expat through version 2.8.3. A specially crafted well-formed XML document can trigger quadratic CPU consumption in storeAtts().
A network-exploitable vulnerability affecting the expat2 package on FreeBSD, with a high availability impact (CVSS v3: A:H).
A prior Expat vulnerability whose fix introduced CVE-2026-76641. The content provides no further technical details.
A quadratic-complexity denial-of-service flaw in Expat's storeAtts() processing. A remote unauthenticated attacker can submit a well-formed XML document with many specified, non-normalized attributes to consume excessive CPU.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.