Is CVE-2021-38509 in the CISA KEV catalog?

No. CVE-2021-38509 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-38509?

CVE-2021-38509 has a CVSS v3 base score of 4.3 (MEDIUM).

What is the EPSS score for CVE-2021-38509?

CVE-2021-38509 has an EPSS score of 1.62% (73th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-38509?

Upgrade firefox on debian unstable to 94.0-1 or later. Fixes are available for 7 affected products.

CVE & CISA-KEV Catalog

CVE-2021-38509

MEDIUMEPSS 73th pctl

4.3

CVSS v3

NVD

Description

Due to an unusual sequence of attacker-controlled events, a Javascript alert() dialog with arbitrary (although unstyled) contents could be displayed over top an uncontrolled webpage of the attacker's choosing. This vulnerability affects Firefox < 94, Thunderbird < 91.3, and Firefox ESR < 91.3.

CWE-1021

How to fix

Remediation Available

firefoxDebian

Fixed in:94.0-1CVE-2021-38509

firefoxUbuntu

Fixed in:94.0+build3-0ubuntu0.18.04.1USN-5131-1

Fixed in:94.0+build3-0ubuntu0.20.04.1USN-5131-1

thunderbirdUbuntu

Fixed in:1:91.5.0+build1-0ubuntu0.18.04.1USN-5248-1

Fixed in:1:91.5.0+build1-0ubuntu0.20.04.1USN-5248-1

DeveloperEditionWindows application

Affected:94.0Fixed in:94.0Mozilla

Mozilla Firefox (en-US)Windows application

Affected:94.0Fixed in:94.0Mozilla

Mozilla Firefox ESR (en-US)Windows application

Affected:91.3.0Fixed in:91.3.0Mozilla

Mozilla Thunderbird (en-US)Windows application

Affected:91.3.0Fixed in:91.3.0Mozilla

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

ConfidentialityNone

IntegrityLow

AvailabilityNone

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

Exploit Intelligence

1.62%probability of exploitation in 30 days

73rdpercentile

Elevated risk: more likely to be exploited than 73% of all known CVEs.

References

Vendor Advisory4

Third-Party Advisory6

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Markdown

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HTML

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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.