CVE-2026-100376 Wikimedia Foundation CVE debrief

Who should care

Defenders responsible for Mediawiki deployments using the TemplateSandbox Extension should assess exposure and prioritize patching or mitigation. They should verify versions and apply patches to prevent potential XSS attacks. Successful exploitation could lead to unauthorized script execution, and defenders should monitor for potential XSS attacks. Remediation priority is medium due to the CVSS score of 4.8.

Why it matters

CVE-2026-100376 is a Cross-Site Scripting (XSS) vulnerability in the Mediawiki - TemplateSandbox Extension. Defenders should prioritize verifying versions and applying patches to prevent potential XSS attacks. Successful exploitation could lead to unauthorized script execution. The CVSS score is 4.8, indicating a medium severity vulnerability.

• Defenders should verify versions and apply patches to prevent potential XSS attacks
• Successful exploitation could lead to unauthorized script execution
• Defenders should monitor for potential XSS attacks
• Remediation priority is medium due to the CVSS score of 4.8

Technical summary

The Mediawiki - TemplateSandbox Extension is vulnerable to Cross-Site Scripting (XSS). This issue affects Mediawiki - TemplateSandbox Extension: from * before 1.46.1, 1.45.5, 1.43.10. The vulnerability allows for unauthorized script execution, potentially leading to security breaches. Successful exploitation requires user interaction, and defenders should verify versions and apply patches to prevent potential XSS attacks. The CVSS score is 4.8, indicating a medium severity vulnerability. Defenders should prioritize verifying the versions of Mediawiki - TemplateSandbox Extension in use and applying patches or mitigations as available.

Defensive priority

Defenders should prioritize verifying the versions of Mediawiki - TemplateSandbox Extension in use and applying patches or mitigations as available.

Recommended defensive actions

• Verify the versions of Mediawiki - TemplateSandbox Extension in use
• Apply patches or mitigations as available
• Monitor for potential XSS attacks
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and NVD entry provide details on the vulnerability, including its description, CVSS score, and affected versions. The Mediawiki - TemplateSandbox Extension is vulnerable to Cross-Site Scripting (XSS). Defenders should prioritize verifying the versions of Mediawiki - TemplateSandbox Extension in use and applying patches or mitigations as available. Evidence is limited to CVE and NVD entries, and further verification is recommended.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.