CVE-2026-8857: A vulnerability in Wikimedia Foundation timeline. This vulnerability is associated with program files script

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HIGH 8.8UPGRADE

CVE-2026-8857 is a high-severity flaw (CVSS 8.8) affecting mediawiki. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

High severity
Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	8.8 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	2.1% (top 18%)
CISA exploited list	No
Weakness	CWE-94
Published	2026-07-01
Last modified	2026-10-25

Publisher (CNA): wikimedia-foundation · Vendor: mediawiki

Last updated 2026-10-25 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-07-01 16:16 UTCPublished CVE record published
2026-10-25 17:10 UTCUpdated Record last modified

mediawiki mediawiki UPGRADE

Affected: >= 1.43.0 and < 1.43.9 · >= 1.44.0 and < 1.44.6 · >= 1.45.0 and < 1.45.4

Fixed in: 1.43.9, 1.44.6, 1.45.4

Safe to downgrade to: a release before 1.43.0

1. Check installed version

apt-cache policy mediawiki || rpm -q mediawiki || mediawiki --version

2. UPGRADE to 1.43.9 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade mediawiki

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade mediawiki

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 1.43.0 (Debian / Ubuntu)

apt-cache madison mediawiki sudo apt install mediawiki=<VERSION_BEFORE_1.43.0> sudo apt-mark hold mediawiki

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list mediawiki sudo dnf downgrade mediawiki-<VERSION_BEFORE_1.43.0> sudo dnf versionlock add mediawiki

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Nuclei scan template: MediaWiki EasyTimeline - Code Injection RCE

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-8857?

mediawiki: upgrade to 1.43.9, 1.44.6, 1.45.4. Exact commands for each OS are on this page.

Is CVE-2026-8857 being exploited?

CVE-2026-8857 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-8857 affect?

CVE-2026-8857 affects mediawiki. Severity is high (CVSS 8.8). 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.

How urgent is CVE-2026-8857?

Priority 56/100. High severity; Public exploit reference

Software pages

PHP vulnerabilities

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References

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