CVE-2023-5725Network attack vector

Sensitive-data exposure via unrestricted extension URL opening

Published Oct 24, 2023 · Updated Feb 13, 2025

URL authorization flaws in Mozilla Firefox before 119, Firefox ESR before 115.4, and Thunderbird before 115.4.1 allow attackers to read data. The WebExtensions windows.create implementation substituted a target-derived triggering principal when the extension principal could not open a requested URL instead of rejecting the restricted URL. A malicious installed WebExtension and user interaction are required; the flaw exposes data obtainable through otherwise restricted URLs without permitting script injection into protected about pages.

CVSS severity4.3
Medium
EPSS probability0.91%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

URL authorization flaws in Mozilla Firefox before 119, Firefox ESR before 115.4, and Thunderbird before 115.4.1 allow attackers to read data. The WebExtensions windows.create implementation substituted a target-derived triggering principal when the extension principal could not open a requested URL instead of rejecting the restricted URL. A malicious installed WebExtension and user interaction are required; the flaw exposes data obtainable through otherwise restricted URLs without permitting script injection into protected about pages.

The record

CVE
CVE-2023-5725
Published
Oct 24, 2023
Updated
Feb 13, 2025
Vendor
Mozilla
Product
Firefox
Classifications
T1005
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 24, 2023CVE publishedPublication date reported by the CVE source.
  2. Feb 13, 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 <119

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mozilla · Firefoxversion=unspecified <119
Mozilla · Thunderbirdversion=unspecified <115.4.1
Mozilla · Firefox ESRversion=unspecified <115.4

Published CVSS scores

4.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/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.

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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

T1005Data from Local System

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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