Go html/template meta content URL escaping bypass XSS
CVE-2026-39823 is a cross-site scripting vulnerability in Go's html/template package involving URL escaping within a <meta> tag's content attribute. The flaw is a bypass in the contextual escaper: when attacker-controlled URL content inserted ASCII whitespace around the '=' character inside the content attribute value, the escaper did not correctly sanitize and escape the input for that context. As a result, malformed attribute content could break out of the intended URL/value interpretation and be rendered in a way that enables script injection in generated HTML. The issue is described as related to the earlier CVE-2026-27142 fix, with this CVE covering the meta content attribute case. The fix sanitizes whitespace in dynamic inputs before escaping.
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Impact
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Mitigation
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Exploits
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No public exploit code observed for this vulnerability.
Affected products & vendors
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Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
Recent activity
11 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
The version that knows your environment.
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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.