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CVE-2026-21513 is a security feature bypass vulnerability in the Microsoft MSHTML Framework. The flaw is located in hyperlink navigation handling within ieframe.dll, specifically in the _AttemptShellExecuteForHlinkNavigate function. Available reporting indicates the vulnerable logic does not strictly validate URLs or navigation targets passed to this routine, allowing content processed by the MSHTML engine to escape the intended browser or trust context. In observed exploitation, attackers used crafted shortcut files and malicious HTML content that caused MSHTML to invoke shell execution behavior for local or remote resources outside the expected security boundaries. The vulnerability was exploited as a zero-day and has been associated with attacks using weaponized LNK files and embedded HTML content to bypass file execution and trust prompts.
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No public exploit code observed for this vulnerability.
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177 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A Microsoft MSHTML/ieframe.dll security feature bypass vulnerability involving hyperlink navigation validation flaws that can reach ShellExecuteExW and execute local or remote resources outside the intended browser security context.
A zero-day vulnerability in the Microsoft MSHTML framework's handling of hyperlinks in ieframe.dll that can be triggered via a crafted .lnk file embedding HTML content.
An MSHTML security bypass vulnerability identified as one of the CVEs being tested by the malware delivery infrastructure.
A specific vulnerability referenced only as smaller test material in the exposed lab; no technical details are provided in the content.
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.