How severe is CVE-2020-15661?

CVE-2020-15661 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2020-15661 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (54th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-15661?

CVE-2020-15661 affects Mozilla Firefox. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2020-15661?

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

When was CVE-2020-15661 published?

CVE-2020-15661 was published on 2020-08-10 and last updated on 2026-06-17.

CVE-2020-15661

CVE-2020-15661 is a medium-severity vulnerability in Mozilla Firefox with a CVSS 3.x base score of 6.5. 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-522.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v2: 4.3
EPSS exploit prediction: 1% (54th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-522
Affected product: Mozilla Firefox
Published: 2020-08-10
Last modified: 2026-06-17

Description

A rogue webpage could override the injected WKUserScript used by the logins autofill, this exploit could result in leaking a password for the current domain. This vulnerability affects Firefox for iOS < 28.

Frequently asked questions

What is CVE-2020-15661?: A rogue webpage could override the injected WKUserScript used by the logins autofill, this exploit could result in leaking a password for the current domain. This vulnerability affects Firefox for iOS < 28.
How severe is CVE-2020-15661?: CVE-2020-15661 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2020-15661 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (54th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-15661?: CVE-2020-15661 affects Mozilla Firefox. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2020-15661?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2020-15661 published?: CVE-2020-15661 was published on 2020-08-10 and last updated on 2026-06-17.

References

Affected products (1)

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

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