CVE-2021-30458

An issue was discovered in Wikimedia Parsoid before 0.11.1 and 0.12.x before 0.12.2. An attacker can send crafted wikitext that Utils/WTUtils.php will transform by using a <meta> tag, bypassing sanitization steps, and potentially allowing for XSS.

Published: 2021-04-09 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-30458 is rated Moderate Risk (45.2/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 0.37%). Review affected assets and schedule remediation.

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

Exploit prediction scoring system (EPSS) score for CVE-2021-30458

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 2026-04-16 0.21% 0.37% +0.16%
2 2025-11-21 0.42% 0.21% -0.21%
3 2025-11-18 — 0.42% —

Full EPSS history (13 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-30458

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.1 3.1 MEDIUM
CVSS:3.1/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-2021-30458

GitHub Security Advisory for CVE-2021-30458

GHSA-5pqx-77vf-85rw · Severity: medium · Ecosystem: composer — Wikimedia Parsoid vulnerable to Cross-site Scripting (XSS)

OS Trackers for CVE-2021-30458

vendor priority summary link
debian not yet assigned CVE-2021-30458 not yet assigned priority: Debian including 1 source packages (mediawiki), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2021-30458
gentoo low CVE-2021-30458: 1 GLSA(s) (202107-40), 1 atom(s) (www-apps/mediawiki); latest impact low. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2021-30458
ubuntu medium CVE-2021-30458 medium priority: Ubuntu including 1 source packages (mediawiki), 16 status rows across 16 suites (bionic, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): ignored 8, needs-triage 5, DNE 2, released 1. https://ubuntu.com/security/CVE-2021-30458

Affected software / configurations for CVE-2021-30458

Vendor Product Version Raw CPE
wikimedia parsoid < 0.11.1 cpe:2.3:a:wikimedia:parsoid:*:*:*:*:*:node.js:*:*
wikimedia parsoid >= 0.12.0, < 0.12.2 cpe:2.3:a:wikimedia:parsoid:*:*:*:*:*:node.js:*:*

References for CVE-2021-30458

URL Tags
https://phabricator.wikimedia.org/T279451 Issue Tracking Vendor Advisory
https://security.gentoo.org/glsa/202107-40 Third Party Advisory
https://www.mediawiki.org/wiki/Parsoid Vendor Advisory
cvelogic Threat Intelligence