CVE-2020-15680

Severity: medium (CVSS 5.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.9% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2020-10-22 · updated 2026-06-17

Description

If a valid external protocol handler was referenced in an image tag, the resulting broken image size could be distinguished from a broken image size of a non-existent protocol handler. This allowed an attacker to successfully probe whether an external protocol handler was registered. This vulnerability affects Firefox < 82.

Affected products

Mozilla Firefox: before 82.0 — fixed in 82.0

How to fix

Upgrade to a fixed version: Mozilla Firefox 82.0. Check the vendor advisory for mitigations.

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1658881
https://www.mozilla.org/security/advisories/mfsa2020-45/
https://bugzilla.mozilla.org/show_bug.cgi?id=1658881
https://www.mozilla.org/security/advisories/mfsa2020-45/

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