CVE-2018-20583
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.,…
Does this matter?
Lower severity and a low EPSS score (1.86%). Track it; it rarely justifies an emergency change on its own.
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).
- CVSS 3.0
- 6.1 MEDIUMCVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
- EPSS
- 1.86% probability · 79th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-79
- Affected
- thephpleague/commonmark
- Source
- cve@mitre.org
EPSS 1.9% since 27 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
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
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.