CVE-2018-20583

Exp

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).

Published: 2018-12-30 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2018-20583 is rated High Exploit Risk (64.5/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 0.34%). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2018-20583

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2018-20583

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2024-12-17 0.12% 0.34% +0.22%
2 2023-03-07 1.14% 0.12% -1.02%
3 2022-02-04 — 1.14% —

Full EPSS history (4 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2018-20583

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.1 3.0 MEDIUM
CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 2.8 2.7 [email protected]
4.3 2.0 MEDIUM
AV:N/AC:M/Au:N/C:N/I:P/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:N)
No availability impact.
 8.6 2.9 [email protected]

Weakness enumeration for CVE-2018-20583

GitHub Security Advisory for CVE-2018-20583

GHSA-qx76-c53f-5c7q · Severity: medium · Ecosystem: composer — PHP League CommonMark vulnerable to Cross-Site Scripting (XSS)

Affected software / configurations for CVE-2018-20583

Vendor Product Version Raw CPE
thephpleague commonmark >= 0.15.6, <= 0.18.0 cpe:2.3:a:thephpleague:commonmark:*:*:*:*:*:*:*:*

References for CVE-2018-20583

URL Tags
https://commonmark.thephpleague.com/changelog/ Release Notes Third Party Advisory
https://github.com/thephpleague/commonmark/issues/337 Exploit Third Party Advisory
https://github.com/thephpleague/commonmark/releases/tag/0.18.1 Release Notes Third Party Advisory
cvelogic Threat Intelligence