CVE-2026-40890: Go Markdown has an Out-of-bounds Read in SmartypantsRenderer

April 14, 2026 (updated April 27, 2026)

Processing a malformed input containing a < character that is not followed by a > character anywhere in the remaining text with a SmartypantsRenderer will lead to Out of Bounds read or a panic.

References

github.com/advisories/GHSA-77fj-vx54-gvh7
github.com/gomarkdown/markdown
github.com/gomarkdown/markdown/commit/759bbc3e32073c3bc4e25969c132fc520eda2778
github.com/gomarkdown/markdown/security/advisories/GHSA-77fj-vx54-gvh7
nvd.nist.gov/vuln/detail/CVE-2026-40890

Code Behaviors & Features

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