How severe is CVE-2026-8857?

CVE-2026-8857 has a CVSS score of 8.8/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2026-8857?

Affected package information for CVE-2026-8857 is not yet fully mapped. Check the official advisory links for details.

How do I fix CVE-2026-8857?

Upgrade the affected component to the fixed release for CVE-2026-8857, or apply your distribution's backported patch — distro builds are often patched at an older version number, so check your vendor's advisory rather than the upstream version alone.

How do I detect CVE-2026-8857 in my code and dependencies?

Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).

How do I mitigate CVE-2026-8857 if there is no patch (or I can't update yet)?

Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.

Is CVE-2026-8857 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-8857 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-8857?

CVE-2026-8857 has an EPSS (Exploit Prediction Scoring System) score of 2.1%, placing it in the 81th 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-2026-8857?

CVE-2026-8857 is classified as Code Injection (CWE-94). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

Is there exploit tooling available for CVE-2026-8857?

A Nuclei detection template exists for CVE-2026-8857, meaning automated scanners can fingerprint it. Public exploit tooling significantly increases real-world risk — prioritize patching and ensure detection coverage. Exploit tooling should only ever be used in isolated, authorized testing environments.

When was CVE-2026-8857 published, and has it been updated?

CVE-2026-8857 was published on July 1, 2026 and was last updated on July 15, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🛡️

Not in CISA KEV

HIGH severity

CVE-2026-8857 — mediawiki

HIGH

CVE-2026-8857 is a high-severity (CVSS 8.8) Code Injection vulnerability. A fix is available — see the affected versions and patch details below.

Published

Jul 1, 2026

Updated

Jul 15, 2026

Affected

1 product

Patched

See advisory

Exploits

None indexed

Exploitation data as of Oct 9, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-8857.

EPSS Exploitation Probability

via FIRST.org ↗

2.1%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs81th percentile — riskier than 81% of all scored CVEsHighest risk

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

How urgent is this, really

CVE-2026-8857 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 384,993 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

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.

Affected Products

1 product · 3 configurations

Application

mediawikimediawiki

≥ 1.45.0 && < 1.45.4

range

Detection & mitigation playbook

Vulnerability

Detect
Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).
Fix
Upgrade the affected component to the fixed release for CVE-2026-8857, or apply your distribution's backported patch — distro builds are often patched at an older version number, so check your vendor's advisory rather than the upstream version alone.
Workarounds
Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.

How to detect CVE-2026-8857

A community-maintained Nuclei template exists for this CVE. You can scan for it directly:

nuclei -id cve-2026-8857 -u https://target

Template: MediaWiki EasyTimeline - Code Injection RCE
Severity: high
Impact: Attackers who can submit timeline markup can execute arbitrary OS commands in the context of the EasyTimeline/ploticus process, potentially leading to full host compromise where Timeline is not isolated (for example outside a remote shellbox).
Remediation: Upgrade the Timeline / EasyTimeline extension to 1.46.0, 1.45.4, 1.44.6, or 1.43.9 (or later). If an upgrade is not immediately possible, disable the EasyTimeline extension, especially when it is not executed in an isolated shellbox.

Template by ProjectDiscovery nuclei-templates (pdteam), MIT licensed. View the full template. Scan only systems you are authorised to test.

Frequently Asked Questions

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.

O3 Security · Impact-Aware SCA

Is CVE-2026-8857 in your dependencies?

Find it across , including transitive dependencies.

Scan my dependencies How O3 SCA works