What’s Vulnerable › Vulnerabilities

CVE-2018-20583

• Severity: medium (CVSS 6.1 v3.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.9% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2018-12-30 · updated 2026-06-17
• Weakness: CWE-79

Description

Cross-site scripting (XSS) vulnerability in the PHP League CommonMark library versions 0.15.6 through 0.18.x before 0.18.1 allows remote attackers to insert unsafe URLs into HTML (even if allow_unsafe_links is false) via a newline character (e.g., writing javascript as javascri%0apt).

Affected products

• thephpleague commonmark: from 0.15.6 through 0.18.0

References

• https://commonmark.thephpleague.com/changelog/
• https://github.com/thephpleague/commonmark/issues/337
• https://github.com/thephpleague/commonmark/releases/tag/0.18.1
• https://commonmark.thephpleague.com/changelog/
• https://github.com/thephpleague/commonmark/issues/337
• https://github.com/thephpleague/commonmark/releases/tag/0.18.1

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