CVE-2026-39840

Name: CVE-2026-39840
Creator: NVD / NIST
Published: 2026-04-07T20:16:33.923+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.1/10EPSS 0.16%

Last modified Jun 17, 2026

CVE-2026-39840 is a medium-severity vulnerability rated 5.1/10 on the CVSS scale. Improper neutralization of input during web page generation ('cross-site scripting') vulnerability in Wikimedia Foundation Mediawiki - Cargo Extension allows XSS Targeting Non-Script Elements.This issue affects Mediawiki - Cargo Extension: before 3.8.7.. EPSS estimates a 0.16% chance of exploitation in the next 30 days.

Description

Improper neutralization of input during web page generation ('cross-site scripting') vulnerability in Wikimedia Foundation Mediawiki - Cargo Extension allows XSS Targeting Non-Script Elements.This issue affects Mediawiki - Cargo Extension: before 3.8.7.

Metrics

CVSS 3.1

6.1/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

CVSS 4.0

5.1/10

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS Probability

0.16%

5.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-79

Affected Software

Vendor	Product	Versions
Mediawiki	Cargo	< 3.8.7

References

https://gerrit.wikimedia.org/r/c/mediawiki/extensions/Cargo/+/1237966Patch
https://phabricator.wikimedia.org/T416368Exploit, Issue Tracking, Vendor Advisory

Timeline

Published: Apr 7, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-39840?

How severe is CVE-2026-39840?

CVE-2026-39840 has a CVSS score of 5.1/10 (MEDIUM severity). The EPSS model estimates a 0.16% probability of exploitation in the next 30 days.

How do I fix CVE-2026-39840?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-39840?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST