XSS in Yuin Goldmark

CVE-2026-5160

Versions of the package github.com/yuin/goldmark/renderer/html before 1.7.17 are vulnerable to Cross-site Scripting (XSS) due to improper ordering of URL validation and normalization. The renderer validates link destinations using a prefix-based check (IsDangerousURL) before resolving HTML entities. This allows an attacker to bypass protocol filtering by encoding dangerous schemes using HTML5 named character references. For example, a payload such as javascript:alert(1) is not recognized as dangerous during validation, leading to arbitrary script execution in the context of applications that render the URL.

Vulnerability class: XSS (Cross-Site Scripting)

EPSS: 0.003 (20.9th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

Affected products

  • Yuin Goldmark
  • N/a Github.com/yuin/goldmark/renderer/html — versions 0

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-5160?
CVE-2026-5160 is a medium-severity vulnerability in Yuin Goldmark, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2026-04-15.
How severe is CVE-2026-5160?
Medium severity. CVSS v3 base score is 6.1 out of 10.