Is CVE-2021-29953 in the CISA KEV catalog?

No. CVE-2021-29953 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-29953?

CVE-2021-29953 has a CVSS v3 base score of 6.1 (MEDIUM).

What is the EPSS score for CVE-2021-29953?

CVE-2021-29953 has an EPSS score of 0.65% (47th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-29953?

Upgrade DeveloperEdition to 88.1.3 or later. Fixes are available for 2 affected products.

CVE & CISA-KEV Catalog

CVE-2021-29953

MEDIUM

6.1

CVSS v3

NVD

Description

A malicious webpage could have forced a Firefox for Android user into executing attacker-controlled JavaScript in the context of another domain, resulting in a Universal Cross-Site Scripting vulnerability. *Note: This issue only affected Firefox for Android. Other operating systems are unaffected. Further details are being temporarily withheld to allow users an opportunity to update.*. This vulnerability affects Firefox < 88.0.1 and Firefox for Android < 88.1.3.

CWE-79Cross-Site Scripting (XSS)

How to fix

Remediation Available

DeveloperEditionWindows application

Affected:88.1.3Fixed in:88.1.3Mozilla

Affected:88.0.1Fixed in:88.0.1Mozilla

Mozilla Firefox (en-US)Windows application

Affected:88.1.3Fixed in:88.1.3Mozilla

Affected:88.0.1Fixed in:88.0.1Mozilla

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

ScopeChanged

Impact

ConfidentialityLow

IntegrityLow

AvailabilityNone

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

Exploit Intelligence

0.65%probability of exploitation in 30 days

47thpercentile

Moderate risk: more likely to be exploited than 47% of all known CVEs.

References

Vendor Advisory2

Related Vulnerabilities

Other CWE-79 (Cross-Site Scripting (XSS)) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2020-11022	Medium	6.9	99%	-	Fix
CVE-2019-3929	Critical	9.8	99%	KEV	Fix
CVE-2020-9496	Medium	6.1	99%	-	-
CVE-2023-28341	Medium	6.1	99%	-	Fix
CVE-2018-12998	Medium	6.1	98%	-	-
CVE-2025-4123	High	7.6	98%	-	Fix

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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.