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CVE-2026-27178: MajorDoMo Stored Cross-Site Scripting via Method Parameters to Shoutbox

• Severity: medium (CVSS 6.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-02-18 · updated 2026-06-17
• Weakness: CWE-79

Description

MajorDoMo (aka Major Domestic Module) contains a stored cross-site scripting (XSS) vulnerability through method parameter injection into the shoutbox. The /objects/?method= endpoint allows unauthenticated execution of stored methods with attacker-controlled parameters. Default methods such as ThisComputer.VolumeLevelChanged pass the user-supplied VALUE parameter directly into the say() function, which stores the message raw in the shouts database table without escaping. The shoutbox widget renders stored messages without sanitization in both PHP rendering code and HTML templates. Because the dashboard widget auto-refreshes every 3 seconds, the injected script executes automatically when any administrator loads the dashboard, enabling session hijack through cookie exfiltration.

Affected products

• sergejey MajorDoMo: all versions

References

• https://chocapikk.com/posts/2026/majordomo-revisited/
• https://github.com/sergejey/majordomo/pull/1177
• https://www.vulncheck.com/advisories/majordomo-stored-cross-site-scripting-via-method-parameters-to-shoutbox

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