CVE-2025-11712Network attack vector

Cross-site scripting via OBJECT content-type override

Published Oct 14, 2025 · Updated Oct 14, 2025

Cross-site scripting in Firefox before 144, Firefox ESR before 140.4, and Thunderbird before 144 allows remote attackers to inject script. The OBJECT element handler trusts its type attribute to override default handling when a fetched resource lacks a Content-Type header. Exploitation requires a user to load a malicious page and a target site to serve a resource without that header, allowing script execution in the target site's origin.

CVSS severity6.1
Medium
EPSS probability0.27%
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 Firefox before 144, Firefox ESR before 140.4, and Thunderbird before 144 allows remote attackers to inject script. The OBJECT element handler trusts its type attribute to override default handling when a fetched resource lacks a Content-Type header. Exploitation requires a user to load a malicious page and a target site to serve a resource without that header, allowing script execution in the target site's origin.

The record

CVE
CVE-2025-11712
Published
Oct 14, 2025
Updated
Oct 14, 2025
Vendor
Mozilla
Product
Firefox
Classifications
CWE-116, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 14, 2025CVE publishedPublication date reported by the CVE source.
  2. Oct 14, 2025Record 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=unspecified <144

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mozilla · Firefoxversion=unspecified <144
Mozilla · Thunderbirdversion=unspecified <140.4; version=unspecified <144
Mozilla · Firefox ESRversion=unspecified <140.4

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-116Improper Encoding or Escaping of Output
T1189Drive-by Compromise

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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