CVE-2018-20583

Name: CVE-2018-20583
Creator: NVD / NIST
Published: 2018-12-30T05:29:00.753+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

UnknownEPSS 1.60%

Last modified Jun 17, 2026

CVE-2018-20583 is a vulnerability of currently unknown severity. 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).. EPSS estimates a 1.60% chance of exploitation in the next 30 days.

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).

Metrics

EPSS Probability

1.60%

72.7th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-79

Affected Software

Vendor	Product	Versions
Thephpleague	Commonmark	>= 0.15.6, <= 0.18.0

References

https://commonmark.thephpleague.com/changelog/Release Notes, Third Party Advisory
https://github.com/thephpleague/commonmark/issues/337Exploit, Third Party Advisory
https://github.com/thephpleague/commonmark/releases/tag/0.18.1Release Notes, Third Party Advisory
https://commonmark.thephpleague.com/changelog/Release Notes, Third Party Advisory
https://github.com/thephpleague/commonmark/issues/337Exploit, Third Party Advisory
https://github.com/thephpleague/commonmark/releases/tag/0.18.1Release Notes, Third Party Advisory

Timeline

Published: Dec 30, 2018
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2018-20583?

How severe is CVE-2018-20583?

Severity scoring for CVE-2018-20583 is pending analysis. The EPSS model estimates a 1.60% probability of exploitation in the next 30 days.

How do I fix CVE-2018-20583?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2018-20583?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST