CVE-2026-8857 Full RCE using EasyTimeline Extension

What is CVE-2026-8857?

CVE-2026-8857 is a code injection vulnerability in Mediawiki Mediawiki, published on 1 Jul 2026. Any signed-in user can exploit it over the network, with no action from the victim.

Official description

A vulnerability in Wikimedia Foundation timeline.

This vulnerability is associated with program files scripts/EasyTimeline.Pl, includes/Timeline.Php.

This issue affects timeline: from * before 1.46.0, 1.45.4, 1.44.6, 1.43.9.

Weakness: CWE-94

Which versions are affected by CVE-2026-8857?

It affects 1 product.

Products include Mediawiki Mediawiki.

How do I fix CVE-2026-8857?

Upgrade to a fixed version.

Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.

Is CVE-2026-8857 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-8857 exists.

Public exploit code: 1 Nuclei template.

Other vulnerabilities in Mediawiki Mediawiki

• CVE-2023-37303 Denial of service in n/a Critical 9.8
• CVE-2022-29904 SQL injection in n/a Critical 9.8
• CVE-2022-29906 Missing authorization in n/a Critical 9.8
• CVE-2022-28205 Business logic in n/a Critical 9.8
• CVE-2022-28206 Missing authorization in n/a Critical 9.8

All Mediawiki Mediawiki vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-q6xp-j96f-7vmp, MINI-5q25-vwpj-2f9v, MINI-5v9m-qvmm-969j, MINI-w46q-xr4h-982h.