How severe is CVE-2018-4277?

CVE-2018-4277 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-2018-4277 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (77th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2018-4277?

CVE-2018-4277 primarily affects Apple Safari. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2018-4277?

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-2018-4277 published?

CVE-2018-4277 was published on 2019-01-11 and last updated on 2026-06-17.

CVE-2018-4277

CVE-2018-4277 is a high-severity vulnerability in Apple Safari 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-20.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 2% (77th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-20
Affected product: Apple Safari
Published: 2019-01-11
Last modified: 2026-06-17

Description

In iOS before 11.4.1, watchOS before 4.3.2, tvOS before 11.4.1, Safari before 11.1.1, macOS High Sierra before 10.13.6, a spoofing issue existed in the handling of URLs. This issue was addressed with improved input validation.

Frequently asked questions

What is CVE-2018-4277?: In iOS before 11.4.1, watchOS before 4.3.2, tvOS before 11.4.1, Safari before 11.1.1, macOS High Sierra before 10.13.6, a spoofing issue existed in the handling of URLs. This issue was addressed with improved input validation.
How severe is CVE-2018-4277?: CVE-2018-4277 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-2018-4277 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (77th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2018-4277?: CVE-2018-4277 primarily affects Apple Safari. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2018-4277?: 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-2018-4277 published?: CVE-2018-4277 was published on 2019-01-11 and last updated on 2026-06-17.

References

Affected products (5)

cpe:2.3:a:apple:safari:*:*:*:*:*:*:*:*
cpe:2.3:o:apple:iphone_os:*:*:*:*:*:*:*:*
cpe:2.3:o:apple:mac_os_x:*:*:*:*:*:*:*:*
cpe:2.3:o:apple:tvos:*:*:*:*:*:*:*:*
cpe:2.3:o:apple:watchos:*:*:*:*:*:*:*:*

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