CVE-2020-26977

Name: CVE-2020-26977
Creator: NVD / NIST
Published: 2021-01-07T14:15:12.237+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.5/10EPSS 0.85%

Last modified Jun 17, 2026

CVE-2020-26977 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. By attempting to connect a website using an unresponsive port, an attacker could have controlled the content of a tab while the URL bar displayed the original domain. *Note: This issue only affects Firefox for Android. EPSS estimates a 0.85% chance of exploitation in the next 30 days.

Description

By attempting to connect a website using an unresponsive port, an attacker could have controlled the content of a tab while the URL bar displayed the original domain. *Note: This issue only affects Firefox for Android. Other operating systems are unaffected.*. This vulnerability affects Firefox < 84.

Metrics

CVSS 3.1

6.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N

EPSS Probability

0.85%

53.5th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Vendor	Product	Versions
Mozilla	Firefox	< 84.0

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1676311Permissions Required
https://www.mozilla.org/security/advisories/mfsa2020-54/Vendor Advisory
https://bugzilla.mozilla.org/show_bug.cgi?id=1676311Permissions Required
https://www.mozilla.org/security/advisories/mfsa2020-54/Vendor Advisory

Timeline

Published: Jan 7, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-26977?

How severe is CVE-2020-26977?

CVE-2020-26977 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 0.85% probability of exploitation in the next 30 days.

How do I fix CVE-2020-26977?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2020-26977?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST