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CVE-2026-40890

Gomarkdown Markdown out-of-bounds read

7.5 HIGHPublic exploitEPSS 0.52%
  1. Published21 Apr 2026

Description

The package `github.com/gomarkdown/markdown` is a Go library for parsing Markdown text and rendering as HTML. 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. This vulnerability is fixed with commit 759bbc3e32073c3bc4e25969c132fc520eda2778.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityNone
IntegrityNone
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

Gomarkdown Markdown< 2026-04-10

Remediation

Fixed in
Gomarkdown Markdown≥ 2026-04-10

References

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Frequently asked

Is CVE-2026-40890 being actively exploited?

CVE-2026-40890 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 0.52%.

How severe is CVE-2026-40890?

CVE-2026-40890 has a CVSS 3.1 base score of 7.5, rated high. EPSS estimates a 0.52% probability of exploitation.

Which products are affected by CVE-2026-40890?

Affected products include Gomarkdown Markdown.

How do I fix CVE-2026-40890?

Upgrade affected software to a fixed version, for example Gomarkdown Markdown 2026-04-10 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-40890 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.