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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

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

Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

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 78th 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 October 24, 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

Not in CISA KEV

MEDIUM severity

CVE-2019-16738 — core

MEDIUM

CVE-2019-16738 is a medium-severity (CVSS 5.3) CWE-862 vulnerability in mediawiki/core. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for mediawiki/core — see the affected versions and patch details below.

MediaWiki information disclosure

Also known asGHSA-7hwr-f745-5rwq

Published

Sep 26, 2019

Updated

Oct 24, 2026

Affected

3 pkgs

Patched

3 / 3

Exploits

1 known

Exploitation data as of Nov 6, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

1.8%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs78th percentile — riskier than 78% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

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`composer require mediawiki/core:^1.31.4`
🐘Packagist	`mediawiki/core`	≥ 1.32.0&&< 1.32.4	1.32.4`composer require mediawiki/core:^1.32.4`
🐘Packagist	`mediawiki/core`	≥ 1.33.0&&< 1.33.1	1.33.1`composer require mediawiki/core:^1.33.1`

Affected Products

3 products · 7 configurations

debian linuxdebian

2 versions

9.010.0

fedorafedoraproject

2 versions

3031

Application

mediawikimediawiki

≥ 1.33.0 && < 1.33.1

range

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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
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
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

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?

Find it across Packagist, including transitive dependencies.

Scan my dependencies How O3 SCA works

CVSS Score

5.3/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

None

Availability

None

Raw vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

CWE Classification

CWE-862CWE-862

Weaponization

No Nuclei template or Metasploit module yet. 1 public proof-of-concept reference is listed on this page.

OpenSSF Scorecard

Package health score

security-advisories

4.8/10

Maintained10/10

Code-Review10/10

Branch-Protection0/10

Assessed Nov 2, 2026

Timeline

Disclosed

Sep 26, 2019

First exploit

Mar 31, 2022

Last updated

Oct 24, 2026

Identifiers

CVE-2019-16738

GHSA-7hwr-f745-5rwq

References

Advisoryseclists.org Advisorydebian.org · dsa 4545 Advisorynvd.nist.gov · CVE 2019 16738 Fixphabricator.wikimedia.org · T230402 Weblists.fedoraproject.org · 7OMG3BMUHGWTAPYTK2NXM6CXF6FYLOUO Weblists.fedoraproject.org · QBAOLXETM5BOYQG6OQVHGB2LNLZUXVN6 Webgithub.com · CVE 2019 16738.yaml Weblists.fedoraproject.org · 7OMG3BMUHGWTAPYTK2NXM6CXF6FYLOUO Weblists.fedoraproject.org · QBAOLXETM5BOYQG6OQVHGB2LNLZUXVN6 Weblists.fedoraproject.org · 7OMG3BMUHGWTAPYTK2NXM6CXF6FYLOUO Weblists.fedoraproject.org · QBAOLXETM5BOYQG6OQVHGB2LNLZUXVN6 Packagegithub.com · mediawiki

Related vulnerabilities

This CVE is medium severity; 8 of 8 other CVEs affecting mediawiki/core are rated as high or higher (top: critical).

CVE-2023-45363CVE-2023-29141CVE-2019-12466CVE-2020-25815CVE-2019-12474CVE-2019-12471CVE-2019-12473CVE-2020-25814

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedOct 24, 2026

CVE-2019-16738 — core

EPSS Exploitation Probability

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

Description

Affected Packages

Affected Products

Detection & mitigation playbook

Detect

Fix

Workarounds

Frequently Asked Questions

Is CVE-2019-16738 in your dependencies?