Vulnerability Monitor

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CVE-2019-9803

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.

Security Impact Summary

This vulnerability carries a HIGH severity rating with a CVSS v3.1 score of 7.4, indicating it can be exploited remotely over the network but requires specific conditions to be met without requiring user interaction and does not require pre-existing privileges . The vulnerability impacts confidentiality (data exposure), integrity (unauthorized modifications), for affected systems. Impacting 1 product from mozilla organizations running these solutions should prioritize assessment and patching.

Historical Context

First disclosed in 2019, this vulnerability was reported during a period defined by widespread IoT adoption challenges, mobile security concerns, and the emergence of advanced persistent threat (APT) techniques. Contemporary mitigation strategies focused on secure development practices and third-party component vetting.

Published

2019-04-26T17:29:03.257

Last Modified

2026-06-17T02:44:29.140

Status

Modified

Source

[email protected]

Severity

CVSSv3.0: 7.4 (HIGH)

CVSSv2 Vector

AV:N/AC:M/Au:N/C:P/I:P/A:N

Access Vector: NETWORK
Access Complexity: MEDIUM
Authentication: NONE
Confidentiality Impact: PARTIAL
Integrity Impact: PARTIAL
Availability Impact: NONE

Exploitability Score

8.6

Impact Score

4.9

Weaknesses

Type: Primary
CWE-346

Affected Vendors & Products

Type	Vendor	Product	Version/Range	Vulnerable?
Application	mozilla	firefox	< 66.0	Yes

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1437009 Issue Tracking, Vendor Advisory ([email protected])
https://bugzilla.mozilla.org/show_bug.cgi?id=1515863 Issue Tracking, Permissions Required, Vendor Advisory ([email protected])
https://w3c.github.io/webappsec-upgrade-insecure-requests/ Third Party Advisory ([email protected])
https://www.mozilla.org/security/advisories/mfsa2019-07/ Vendor Advisory ([email protected])
https://bugzilla.mozilla.org/show_bug.cgi?id=1437009 Issue Tracking, Vendor Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://bugzilla.mozilla.org/show_bug.cgi?id=1515863 Issue Tracking, Permissions Required, Vendor Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://w3c.github.io/webappsec-upgrade-insecure-requests/ Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://www.mozilla.org/security/advisories/mfsa2019-07/ Vendor Advisory (af854a3a-2127-422b-91ae-364da2661108)

How SecUtils Interprets This CVE

SecUtils normalizes and enriches National Vulnerability Database (NVD) records by standardizing vendor and product identifiers, aggregating vulnerability metadata from both NVD and MITRE sources, and providing structured context for security teams. For mozilla's affected products, we extract Common Platform Enumeration (CPE) data, Common Weakness Enumeration (CWE) classifications, CVSS severity metrics, and reference data to enable rapid vulnerability prioritization and asset correlation. This record contains no exploit code, proof-of-concept instructions, or attack methodologies—only defensive intelligence necessary for patch management, risk assessment, and security operations.