CVE-2026-84137

Content spoofing through undisclosed DOM flaw

Published Sep 1, 2026 · Updated Sep 3, 2026

Spoofing in Mozilla Firefox, Firefox ESR, Thunderbird, and Thunderbird ESR allows attackers to present misleading content. Mozilla has not published the nature of the flaw or the wrong DOM operation in the Core & HTML component. The required attacker position and user interaction are undisclosed, and the documented consequence is limited to spoofing.

CVSS severityUnavailable
Unscored
EPSS probability0.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Spoofing in Mozilla Firefox, Firefox ESR, Thunderbird, and Thunderbird ESR allows attackers to present misleading content. Mozilla has not published the nature of the flaw or the wrong DOM operation in the Core & HTML component. The required attacker position and user interaction are undisclosed, and the documented consequence is limited to spoofing.

The record

CVE
CVE-2026-84137
Published
Sep 1, 2026
Updated
Sep 3, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
Unavailable
Attack vector
Unavailable
Privileges
Unavailable

Timeline

How it unfolded

  1. Sep 1, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 3, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorUnavailable in this record.
Required privilegesUnavailable in this record.

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

No CVSS assessment is available in this record.

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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
VectorUnavailable
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

No sourced classifications are available.

Public exploit references

No public exploit references are available in this record.

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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