CVE-2020-15655

Name: CVE-2020-15655
Creator: NVD / NIST
Published: 2020-08-10T18:15:12.497+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.5/10EPSS 1.53%

Last modified Jun 17, 2026

CVE-2020-15655 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. A redirected HTTP request which is observed or modified through a web extension could bypass existing CORS checks, leading to potential disclosure of cross-origin information. This vulnerability affects Firefox ESR < 78.1, Firefox < 79, and Thunderbird < 78.1.. EPSS estimates a 1.53% chance of exploitation in the next 30 days.

Description

A redirected HTTP request which is observed or modified through a web extension could bypass existing CORS checks, leading to potential disclosure of cross-origin information. This vulnerability affects Firefox ESR < 78.1, Firefox < 79, and Thunderbird < 78.1.

Metrics

CVSS 3.1

6.5/10

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

EPSS Probability

1.53%

71.5th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Vendor	Product	Versions
Mozilla	Firefox	< 79.0
Mozilla	Firefox Esr	< 78.1
Mozilla	Thunderbird	< 78.1
Opensuse	Leap	15.2
Canonical	Ubuntu Linux	16.04
Canonical	Ubuntu Linux	18.04
Canonical	Ubuntu Linux	20.04

References

http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00025.htmlMailing List, Third Party Advisory
https://bugzilla.mozilla.org/show_bug.cgi?id=1645204Issue Tracking, Vendor Advisory
https://usn.ubuntu.com/4443-1/Third Party Advisory
https://www.mozilla.org/security/advisories/mfsa2020-30/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2020-32/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2020-33/Vendor Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00025.htmlMailing List, Third Party Advisory
https://bugzilla.mozilla.org/show_bug.cgi?id=1645204Issue Tracking, Vendor Advisory
https://usn.ubuntu.com/4443-1/Third Party Advisory
https://www.mozilla.org/security/advisories/mfsa2020-30/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2020-32/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2020-33/Vendor Advisory

Timeline

Published: Aug 10, 2020
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-15655?

How severe is CVE-2020-15655?

CVE-2020-15655 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 1.53% probability of exploitation in the next 30 days.

How do I fix CVE-2020-15655?

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-2020-15655?

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

Scan your code now

Source: NVD / NIST