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MEDIUM severity

CVE-2019-19709 — core

MEDIUM

CVE-2019-19709 is a medium-severity (CVSS 6.1) Open Redirect vulnerability in mediawiki/core. 2 public exploit or proof-of-concept references are indexed, so weaponization risk is real. A fix is available for mediawiki/core — see the affected versions and patch details below.

Possible to circumvent title-blacklist

Also known asGHSA-pjv5-vv93-p648
Published
Updated
Affected
4 pkgs
Patched
4 / 4
Exploits
2 known
Exploitation data as of Nov 4, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.6%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs75th percentile — riskier than 75% of all scored CVEsHighest risk
0.00%0.69%1.38%2.06%0.3%1.6%May 26Sep 26Nov 26

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

4 pkgs affected
🐘mediawiki/core🐘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

MediaWiki through 1.33.1 allows attackers to bypass the Title_blacklist protection mechanism by starting with an arbitrary title, establishing a non-resolvable redirect for the associated page, and using redirect=1 in the action API when editing that page.

Affected Packages

4 total 4 fixed
EcosystemPackageVulnerable rangeFix
🐘Packagistmediawiki/core≥ 1.31.0&&< 1.31.61.31.6composer require mediawiki/core:^1.31.6
🐘Packagistmediawiki/core≥ 1.32.0&&< 1.32.61.32.6composer require mediawiki/core:^1.32.6
🐘Packagistmediawiki/core≥ 1.33.0&&< 1.33.21.33.2composer require mediawiki/core:^1.33.2
🐘Packagistmediawiki/core≥ 1.33.99&&< 1.34.01.34.0composer require mediawiki/core:^1.34.0

Affected Products

2 products · 3 configurations
OS
debian linuxdebian
2 versions
9.010.0
Application
mediawikimediawiki
≤ 1.33.1
range
Exploits & PoCs
2

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

MediaWiki through 1.33.1 allows attackers to bypass the Title_blacklist …

phabricator.wikimedia.orgNVDDec 2019

Report on gerrit.wikimedia.org

gerrit.wikimedia.orgNVDDec 2019

Detection & mitigation playbook

Open-source dependency

  1. 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.

  2. Fix

    Update mediawiki/core to 1.31.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2019-19709 is resolved across your whole dependency graph.

  3. Workarounds

    Stop reflecting attacker-controlled destinations: resolve every redirect target against an allowlist of paths or hosts you own, prefer a server-side key over a full URL in the request, and reject absolute URLs entirely where the flow only ever needs a relative one.

Frequently Asked Questions

MediaWiki through 1.33.1 allows attackers to bypass the Title_blacklist protection mechanism by starting with an arbitrary title, establishing a non-resolvable redirect for the associated page, and using redirect=1 in the action API when editing that page.
O3 Security · Impact-Aware SCA

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CVE-2019-19709: core — Fixed in 1.31.6