Is CVE-2021-23953 in the CISA KEV catalog?

No. CVE-2021-23953 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-23953?

CVE-2021-23953 has a CVSS v3 base score of 4.3 (MEDIUM).

What is the EPSS score for CVE-2021-23953?

CVE-2021-23953 has an EPSS score of 1.05% (60th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-23953?

Upgrade firefox on debian unstable to 85.0-1 or later. Fixes are available for 6 affected products.

CVE & CISA-KEV Catalog

CVE-2021-23953

MEDIUM

4.3

CVSS v3

NVD

Description

If a user clicked into a specifically crafted PDF, the PDF reader could be confused into leaking cross-origin information, when said information is served as chunked data. This vulnerability affects Firefox < 85, Thunderbird < 78.7, and Firefox ESR < 78.7.

How to fix

Remediation Available

firefoxDebian

Fixed in:85.0-1CVE-2021-23953

firefoxUbuntu

Fixed in:85.0+build1-0ubuntu0.16.04.1USN-4717-1

Fixed in:85.0+build1-0ubuntu0.18.04.1USN-4717-1

Fixed in:85.0+build1-0ubuntu0.20.04.1USN-4717-1

DeveloperEditionWindows application

Affected:85.0Fixed in:85.0Mozilla

Mozilla Firefox (en-US)Windows application

Affected:85.0Fixed in:85.0Mozilla

Mozilla Firefox ESR (en-US)Windows application

Affected:78.7Fixed in:78.7Mozilla

Mozilla Thunderbird (en-US)Windows application

Affected:78.7Fixed in:78.7Mozilla

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

ConfidentialityLow

IntegrityNone

AvailabilityNone

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

Exploit Intelligence

1.05%probability of exploitation in 30 days

60thpercentile

Moderate risk: more likely to be exploited than 60% of all known CVEs.

References

Vendor Advisory4

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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.