CVE-2023-23604Network attack vector

Web security bypass via duplicate SystemPrincipal creation

Published Jun 2, 2023 · Updated Dec 18, 2025

Incorrect authorization in Mozilla Firefox before 109 allows remote attackers to bypass web security checks through crafted web content. DOMParser::ParseFromSafeString assigns a new SystemPrincipal while parsing non-system HTML, but Gecko checks system privilege by comparing principal object identity. Exploitation requires user interaction with attacker-controlled content; the published impact is unauthorized integrity modification, not disclosure or service interruption.

CVSS severity6.5
Medium
EPSS probability0.46%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Incorrect authorization in Mozilla Firefox before 109 allows remote attackers to bypass web security checks through crafted web content. DOMParser::ParseFromSafeString assigns a new SystemPrincipal while parsing non-system HTML, but Gecko checks system privilege by comparing principal object identity. Exploitation requires user interaction with attacker-controlled content; the published impact is unauthorized integrity modification, not disclosure or service interruption.

The record

CVE
CVE-2023-23604
Published
Jun 2, 2023
Updated
Dec 18, 2025
Vendor
Mozilla
Product
Firefox
Classifications
CWE-863
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 2, 2023CVE publishedPublication date reported by the CVE source.
  2. Dec 18, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=unspecified <109

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mozilla · Firefoxversion=unspecified <109

Published CVSS scores

6.5CISA ADP VulnrichmentCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/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-863Incorrect Authorization

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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo