How severe is CVE-2023-4055?

CVE-2023-4055 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.

Is CVE-2023-4055 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (45th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2023-4055?

CVE-2023-4055 primarily affects Mozilla Firefox. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2023-4055?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2023-4055 published?

CVE-2023-4055 was published on 2023-08-01 and last updated on 2026-06-17.

CVE-2023-4055

CVE-2023-4055 is a high-severity vulnerability in Mozilla Firefox with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-120.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 1% (45th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-120
Affected product: Mozilla Firefox
Published: 2023-08-01
Last modified: 2026-06-17

Description

When the number of cookies per domain was exceeded in `document.cookie`, the actual cookie jar sent to the host was no longer consistent with expected cookie jar state. This could have caused requests to be sent with some cookies missing. This vulnerability affects Firefox < 116, Firefox ESR < 102.14, and Firefox ESR < 115.1.

Frequently asked questions

What is CVE-2023-4055?: When the number of cookies per domain was exceeded in `document.cookie`, the actual cookie jar sent to the host was no longer consistent with expected cookie jar state. This could have caused requests to be sent with some cookies missing. This vulnerability affects Firefox < 116, Firefox ESR < 102.14, and Firefox ESR < 115.1.
How severe is CVE-2023-4055?: CVE-2023-4055 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.
Is CVE-2023-4055 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (45th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2023-4055?: CVE-2023-4055 primarily affects Mozilla Firefox. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2023-4055?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2023-4055 published?: CVE-2023-4055 was published on 2023-08-01 and last updated on 2026-06-17.

References

Affected products (3)

cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:12.0:*:*:*:*:*:*:*

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