How severe is CVE-2020-9857?

CVE-2020-9857 has a CVSS 3.x base score of 4.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity none, and availability none.

Is CVE-2020-9857 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (51st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-9857?

CVE-2020-9857 affects Apple Mac Os X. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2020-9857?

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

When was CVE-2020-9857 published?

CVE-2020-9857 was published on 2020-10-27 and last updated on 2026-06-17.

CVE-2020-9857

CVE-2020-9857 is a medium-severity vulnerability in Apple Mac Os X with a CVSS 3.x base score of 4.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Severity: Medium (CVSS 3.x base score 4.3)
CVSS v2: 4.3
EPSS exploit prediction: 1% (51st percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Apple Mac Os X
Published: 2020-10-27
Last modified: 2026-06-17

Description

An issue existed in the parsing of URLs. This issue was addressed with improved input validation. This issue is fixed in macOS Catalina 10.15.5, Security Update 2020-003 Mojave, Security Update 2020-003 High Sierra. A malicious website may be able to exfiltrate autofilled data in Safari.

Frequently asked questions

What is CVE-2020-9857?: An issue existed in the parsing of URLs. This issue was addressed with improved input validation. This issue is fixed in macOS Catalina 10.15.5, Security Update 2020-003 Mojave, Security Update 2020-003 High Sierra. A malicious website may be able to exfiltrate autofilled data in Safari.
How severe is CVE-2020-9857?: CVE-2020-9857 has a CVSS 3.x base score of 4.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity none, and availability none.
Is CVE-2020-9857 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (51st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-9857?: CVE-2020-9857 affects Apple Mac Os X. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2020-9857?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2020-9857 published?: CVE-2020-9857 was published on 2020-10-27 and last updated on 2026-06-17.

References

https://support.apple.com/en-us/HT211170

Affected products (1)

cpe:2.3:o:apple:mac_os_x:*:*:*:*:*:*:*:*

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