CVE & CISA-KEV Catalog

CVE-2021-23986

MEDIUM
6.5
CVSS v3
NVD

Description

A malicious extension with the 'search' permission could have installed a new search engine whose favicon referenced a cross-origin URL. The response to this cross-origin request could have been read by the extension, allowing a same-origin policy bypass by the extension, which should not have cross-origin permissions. This cross-origin request was made without cookies, so the sensitive information disclosed by the violation was limited to local-network resources or resources that perform IP-based authentication. This vulnerability affects Firefox < 87.

CWE-346

How to fix

Remediation Available
firefoxDebian
Fixed in:87.0-1CVE-2021-23986
firefoxUbuntu
Fixed in:87.0+build3-0ubuntu0.16.04.2USN-4893-1
Fixed in:87.0+build3-0ubuntu0.18.04.2USN-4893-1
Fixed in:87.0+build3-0ubuntu0.20.04.2USN-4893-1
DeveloperEditionWindows application
Affected:87.0Fixed in:87.0Mozilla
Mozilla Firefox (en-US)Windows application
Affected:87.0Fixed in:87.0Mozilla

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredNone
User InteractionRequired
ScopeUnchanged

Impact

ConfidentialityHigh
IntegrityNone
AvailabilityNone

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

Exploit Intelligence

0.44%probability of exploitation in 30 days
35thpercentile

Low risk: more likely to be exploited than 35% of all known CVEs.

References

Related Vulnerabilities

Other CWE-346 vulnerabilities, ordered by exploit likelihood. View all

CVESeverityCVSSEPSSExploitedFix
CVE-2009-1185High7.282%-Fix
CVE-2025-34291High8.879%KEV-
CVE-2020-16952High8.671%--
CVE-2023-29711Critical9.870%--
CVE-2015-4495High8.870%KEVFix
CVE-2024-23898High8.867%-Fix
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Markdown

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2024-11-21.