CVE-2018-20583 json
PHP League CommonMark vulnerable to Cross-Site Scripting (XSS)
published 2018-12-30 7 y ago modified 2026-06-17 4 mo ago also GHSA-qx76-c53f-5c7q , EUVD-2022-5057
- cvss
- 6.1
- version 3.0, NVD
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 1.9%
- EPSS 1.9% chance of exploitation in 30 days, percentile 79%
- public exploits
- 0
- none known
Summary
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).
Patch / fix
Exploit prediction
1.86% chance of exploitation in the next 30 days, higher than 79% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- github.com https://github.com/thephpleague/commonmark/issues/337 referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| NVD | 3.0 | 6.1 | CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N |
| NVD | 2.0 | 4.3 | AV:N/AC:M/Au:N/C:N/I:P/A:N |
| GitHub | 3.0 | 6.1 | CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| packagist | league/commonmark | >=0.15.6, <0.18.1 |
0.18.1 |
Classification
- Weakness
-
- CWE-79 Improper Neutralization of Input During Web Page Generation
References
-
github.com
/thephpleague/commonmark/issues/337
web, exploit, third-party-advisory
-
commonmark.thephpleague.com
/changelog/
release-notes, third-party-advisory
-
github.com
/thephpleague/commonmark/releases/tag/0.18.1
web, release-notes, third-party-advisory
-
nvd.nist.gov
/vuln/detail/CVE-2018-20583
advisory
-
commonmark.thephpleague.com
/changelog
web
-
github.com
/FriendsOfPHP/security-advisories/blob/master/league/commonmark/CVE-2018-20583.yaml
web
-
github.com
/thephpleague/commonmark
package
Sources
- CVE List CVE-2018-20583
- GitHub Advisory GHSA-qx76-c53f-5c7q
- NVD CVE-2018-20583
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.