Is CVE-2019-9803 in the CISA KEV catalog?

No. CVE-2019-9803 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2019-9803?

CVE-2019-9803 has a CVSS v3 base score of 7.4 (HIGH).

What is the EPSS score for CVE-2019-9803?

CVE-2019-9803 has an EPSS score of 0.56% (43th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2019-9803?

Upgrade firefox on debian unstable to 66.0-1 or later. Fixes are available for 4 affected products.

CVE & CISA-KEV Catalog

CVE-2019-9803

HIGH

7.4

CVSS v3

NVD

Description

The Upgrade-Insecure-Requests (UIR) specification states that if UIR is enabled through Content Security Policy (CSP), navigation to a same-origin URL must be upgraded to HTTPS. Firefox will incorrectly navigate to an HTTP URL rather than perform the security upgrade requested by the CSP in some circumstances, allowing for potential man-in-the-middle attacks on the linked resources. This vulnerability affects Firefox < 66.

CWE-346

How to fix

Remediation Available

firefoxDebian

Fixed in:66.0-1CVE-2019-9803

firefoxUbuntu

Fixed in:66.0.1+build1-0ubuntu0.14.04.1USN-3918-2

Fixed in:66.0+build3-0ubuntu0.16.04.2USN-3918-1

Fixed in:66.0+build3-0ubuntu0.18.04.1USN-3918-1

DeveloperEditionWindows application

Affected:66.0Fixed in:66.0Mozilla

Mozilla Firefox (en-US)Windows application

Affected:66.0Fixed in:66.0Mozilla

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 ComplexityHigh

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityNone

CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

Exploit Intelligence

0.56%probability of exploitation in 30 days

43rdpercentile

Moderate risk: more likely to be exploited than 43% of all known CVEs.

References

Vendor Advisory3

Third-Party Advisory1

w3c.github.io

Related Vulnerabilities

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

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2009-1185	High	7.2	82%	-	Fix
CVE-2025-34291	High	8.8	79%	KEV	-
CVE-2020-16952	High	8.6	71%	-	-
CVE-2023-29711	Critical	9.8	70%	-	-
CVE-2015-4495	High	8.8	70%	KEV	Fix
CVE-2024-23898	High	8.8	67%	-	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.