How severe is CVE-2019-16738?

CVE-2019-16738 has a CVSS score of 5.3/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2019-16738?

CVE-2019-16738 affects the following packages: mediawiki/core (Packagist), mediawiki/core (Packagist), mediawiki/core (Packagist). Ecosystems affected: Packagist.

How do I fix CVE-2019-16738?

Update mediawiki/core to 1.31.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2019-16738 is resolved across your whole dependency graph.

How do I detect CVE-2019-16738 in my Packagist dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for mediawiki/core. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate CVE-2019-16738 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against CVE-2019-16738?

O3 pinpoints whether CVE-2019-16738 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is CVE-2019-16738 actively exploited in the wild?

Yes. There are 1 known exploit references for CVE-2019-16738, including 1 in-the-wild exploitation observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2019-16738?

CVE-2019-16738 has an EPSS (Exploit Prediction Scoring System) score of 1.8%, placing it in the 75th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2019-16738?

CVE-2019-16738 is classified as CWE-862 (CWE-862). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2019-16738 published, and has it been updated?

CVE-2019-16738 was published on September 26, 2019 and was last updated on April 16, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐘 Packagist

CVE-2019-16738

MEDIUM

MediaWiki information disclosure

Also known asGHSA-7hwr-f745-5rwq

Published

Sep 26, 2019

Updated

Apr 16, 2026

Affected

3 pkgs

Patched

3 / 3

Exploits

1 known

EPSS Exploitation Probability

via FIRST.org ↗

1.8%probability of exploitation in next 30 days

Lower Risk75th percentile+1.35%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

3 pkgs affected

🐘mediawiki/core🐘mediawiki/core🐘mediawiki/core

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.

Description

In MediaWiki through 1.33.0, Special:Redirect allows information disclosure of suppressed usernames via a User ID Lookup.

Affected Packages

3 total 3 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`mediawiki/core`	≥ 1.31.0&&< 1.31.4	1.31.4
🐘Packagist	`mediawiki/core`	≥ 1.32.0&&< 1.32.4	1.32.4
🐘Packagist	`mediawiki/core`	≥ 1.33.0&&< 1.33.1	1.33.1

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

In MediaWiki through 1.33.0, Special:Redirect allows information disclos…

phabricator.wikimedia.orgNVDMar 2022

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for mediawiki/core. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update mediawiki/core to 1.31.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2019-16738 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2019-16738 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to CVE-2019-16738. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

In MediaWiki through 1.33.0, Special:Redirect allows information disclosure of suppressed usernames via a User ID Lookup.

O3 Security · Impact-Aware SCA

Is CVE-2019-16738 in your dependencies?

O3 detects CVE-2019-16738 across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my dependencies How O3 SCA works