CVE-2025-6430Public exploitNetwork attack vector

Cross-site scripting via ignored attachment disposition

Published Jun 24, 2025 · Updated Apr 13, 2026

Cross-site scripting in Mozilla Firefox and Thunderbird before 140 and ESR releases before 128.12 allows remote attackers to execute script. The DOM navigation path ignores Content-Disposition: attachment for HTML loaded through object or embed elements and renders the untrusted content instead of downloading it. Exploitation requires a site to host attacker-controlled HTML as an attachment and a user to open a page that embeds it; Thunderbird mail reading disables scripting.

CVSS severity6.1
Medium
EPSS probability0.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site scripting in Mozilla Firefox and Thunderbird before 140 and ESR releases before 128.12 allows remote attackers to execute script. The DOM navigation path ignores Content-Disposition: attachment for HTML loaded through object or embed elements and renders the untrusted content instead of downloading it. Exploitation requires a site to host attacker-controlled HTML as an attachment and a user to open a page that embeds it; Thunderbird mail reading disables scripting.

The record

CVE
CVE-2025-6430
Published
Jun 24, 2025
Updated
Apr 13, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-79, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 24, 2025CVE publishedPublication date reported by the CVE source.
  2. Apr 13, 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 vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

6.1CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:R/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 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')
T1189Drive-by Compromise

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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