CVE-2026-78661: high-severity vulnerability in golang.org/x/net/html
Avoid quadratic complexity when coalescing text nodes in html in golang.org/x/net
Published · Updated
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21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 7.5epss 0.2%
When coalescing adjacent text nodes in addText and fosterParent, appending to an existing TextNode's Data via string concatenation (n.Data += text) reallocated and copied the accumulated string on every token. Inputs containing many short text runs separated by ignored end tags (such as "a</x>") caused O(n^2) allocations and byte copies. Accumulate coalesced text in per-node byte slices during parsing and materialize Data strings once at the end of parse.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Affected products
golang.org/x/net · golang.org/x/net/htmlRelated CVEs — golang.org/x/net/html
In the same product, most dangerous first.
CVE-2024-45338MEDIUMNon-linear parsing of case-insensitive content in golang.org/x/net/htmlEPSS 1.1%CVE-2023-3978—Improper rendering of text nodes in golang.org/x/net/htmlEPSS 0.9%CVE-2025-47911MEDIUMQuadratic parsing complexity in golang.org/x/net/htmlEPSS 0.6%CVE-2025-22872MEDIUMIncorrect Neutralization of Input During Web Page Generation in x/net in golang.org/x/netEPSS 0.5%CVE-2025-58190MEDIUMInfinite parsing loop in golang.org/x/netEPSS 0.5%CVE-2026-25680MEDIUMInvoking denial of service when parsing arbitrary HTML in golang.org/x/net/htmlEPSS 0.3%