How severe is CVE-2015-4503?

CVE-2015-4503 has a CVSS 2.0 base score of 5.0, rated medium severity.

Is CVE-2015-4503 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (72nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2015-4503?

CVE-2015-4503 affects Mozilla Firefox. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2015-4503?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2015-4503 published?

CVE-2015-4503 was published on 2015-09-24 and last updated on 2026-06-17.

CVE-2015-4503

CVE-2015-4503 is a medium-severity vulnerability in Mozilla Firefox with a CVSS 2.0 base score of 5.0. 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-200.

Key facts

Severity: Medium (CVSS 2.0 base score 5.0)
EPSS exploit prediction: 2% (72nd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-200
Affected product: Mozilla Firefox
Published: 2015-09-24
Last modified: 2026-06-17

Description

The TCP Socket API implementation in Mozilla Firefox before 41.0 mishandles array boundaries that were established with a navigator.mozTCPSocket.open method call and send method calls, which allows remote TCP servers to obtain sensitive information from process memory by reading packet data, as demonstrated by availability of this API in a Firefox OS application.

Frequently asked questions

What is CVE-2015-4503?: The TCP Socket API implementation in Mozilla Firefox before 41.0 mishandles array boundaries that were established with a navigator.mozTCPSocket.open method call and send method calls, which allows remote TCP servers to obtain sensitive information from process memory by reading packet data, as demonstrated by availability of this API in a Firefox OS application.
How severe is CVE-2015-4503?: CVE-2015-4503 has a CVSS 2.0 base score of 5.0, rated medium severity.
Is CVE-2015-4503 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (72nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2015-4503?: CVE-2015-4503 affects Mozilla Firefox. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2015-4503?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2015-4503 published?: CVE-2015-4503 was published on 2015-09-24 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*

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