CVE-2024-1555Public exploitNetwork attack vector

Authenticated cross-site requests via privileged protocol handler

Published Feb 20, 2024 · Updated Nov 15, 2024

SameSite enforcement in Mozilla Firefox before 123 allows remote attackers to send protected cookies through an external firefox:// link. The OS-registered firefox and firefox-private handlers create the target load with the system principal instead of an opaque null principal, causing Firefox to treat the external navigation as same-site and send Strict cookies. A user must activate a crafted link in another application and approve the Firefox launch; affected sites must rely on SameSite cookies to prevent authenticated cross-site requests.

CVSS severity8.3
High
EPSS probability0.48%
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

SameSite enforcement in Mozilla Firefox before 123 allows remote attackers to send protected cookies through an external firefox:// link. The OS-registered firefox and firefox-private handlers create the target load with the system principal instead of an opaque null principal, causing Firefox to treat the external navigation as same-site and send Strict cookies. A user must activate a crafted link in another application and approve the Firefox launch; affected sites must rely on SameSite cookies to prevent authenticated cross-site requests.

The record

CVE
CVE-2024-1555
Published
Feb 20, 2024
Updated
Nov 15, 2024
Vendor
Mozilla
Product
Firefox
Classifications
CWE-290, T1204.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 20, 2024CVE publishedPublication date reported by the CVE source.
  2. Nov 15, 2024Record 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 <123

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mozilla · Firefoxversion=unspecified <123

Published CVSS scores

8.3CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:L

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-290Authentication Bypass by Spoofing
T1204.001User Execution: Malicious Link

Public exploit references

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