CVE-2026-27178Public exploitNetwork attack vector

Administrator session hijacking via unescaped shoutbox messages

Published Feb 18, 2026 · Updated Feb 18, 2026

Stored XSS in the MajorDoMo shoutbox allows remote attackers to hijack administrator sessions through injected method parameters. ThisComputer.VolumeLevelChanged passes the untrusted VALUE parameter to say(), which stores it raw, and the shoutbox renders the message without escaping. No authentication is required to store the payload, but an administrator must load the auto-refreshing dashboard for script execution and cookie exfiltration.

CVSS severity5.3
Medium
EPSS probability0.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in the MajorDoMo shoutbox allows remote attackers to hijack administrator sessions through injected method parameters. ThisComputer.VolumeLevelChanged passes the untrusted VALUE parameter to say(), which stores it raw, and the shoutbox renders the message without escaping. No authentication is required to store the payload, but an administrator must load the auto-refreshing dashboard for script execution and cookie exfiltration.

The record

CVE
CVE-2026-27178
Published
Feb 18, 2026
Updated
Feb 18, 2026
Vendor
MajorDoMo
Product
MajorDoMo
Classifications
CWE-79, T1539
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 18, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 18, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <=*

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

MajorDoMo · MajorDoMoversion=0 <=*

Published CVSS scores

5.3VulnCheckCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N
6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
7.2VulnCheckCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1539Steal Web Session Cookie

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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