CVE-2023-4055Public exploitNetwork attack vector

Cookie fixation via cookie jar desynchronization

Published Aug 1, 2023 · Updated Feb 13, 2025

Cookie jar desynchronization in Firefox and Firefox ESR allows remote attackers to fixate cookies via document.cookie overflow. The cookie service fails to evict cookies while AddCookie processes writes beyond the per-domain limit, so document.cookie retains entries absent from the network cookie jar and server deletion attempts. Exploitation requires control of a same-origin or same-site related domain; fixed cookies can influence applications that trust document.cookie values.

CVSS severity7.5
High
EPSS probability0.73%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cookie jar desynchronization in Firefox and Firefox ESR allows remote attackers to fixate cookies via document.cookie overflow. The cookie service fails to evict cookies while AddCookie processes writes beyond the per-domain limit, so document.cookie retains entries absent from the network cookie jar and server deletion attempts. Exploitation requires control of a same-origin or same-site related domain; fixed cookies can influence applications that trust document.cookie values.

The record

CVE
CVE-2023-4055
Published
Aug 1, 2023
Updated
Feb 13, 2025
Vendor
Mozilla
Product
Firefox
Classifications
CWE-120
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 1, 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=0 <116
  2. Affected versionversion=unspecified <116

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mozilla · Firefoxversion=0 <116; version=unspecified <116
Mozilla · Firefox ESRversion=0 <102.14; version=0 <115.1; version=unspecified <102.14; version=unspecified <115.1

Published CVSS scores

7.5NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/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 exploitPublished

Weakness, pattern, technique

CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')

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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