CVE-2024-6611Public exploitNetwork attack vector

Cookie tossing via cross-site iframe navigation

Published Jul 9, 2024 · Updated Oct 30, 2025

Cookie isolation failure in Mozilla Firefox and Thunderbird before 128 allows remote attackers to overwrite SameSite cookies via an iframe. The networking cookie checks accepted Set-Cookie responses during cross-site-to-same-site subdocument navigation instead of limiting the nested context to SameSite=None cookies. A victim must visit a page embedding attacker-controlled content; cookie tossing can log the victim out or support session or CSRF token fixation when the attacker also controls a target-site subdomain.

CVSS severity9.8
Critical
EPSS probability0.66%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cookie isolation failure in Mozilla Firefox and Thunderbird before 128 allows remote attackers to overwrite SameSite cookies via an iframe. The networking cookie checks accepted Set-Cookie responses during cross-site-to-same-site subdocument navigation instead of limiting the nested context to SameSite=None cookies. A victim must visit a page embedding attacker-controlled content; cookie tossing can log the victim out or support session or CSRF token fixation when the attacker also controls a target-site subdomain.

The record

CVE
CVE-2024-6611
Published
Jul 9, 2024
Updated
Oct 30, 2025
Vendor
Mozilla
Product
Firefox
Classifications
CWE-1275, CAPEC-62, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 9, 2024CVE publishedPublication date reported by the CVE source.
  2. Oct 30, 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=0 <128
  2. Affected versionversion=unspecified <128

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mozilla · Firefoxversion=0 <128; version=unspecified <128
Mozilla · Thunderbirdversion=unspecified <128

Published CVSS scores

9.8CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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-1275Sensitive Cookie with Improper SameSite Attribute
CAPEC-62Cross Site Request Forgery
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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