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CVE-2019-9803

The Upgrade-Insecure-Requests (UIR) specification states that if UIR is enabled through Content...

7.4 HighFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
High
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
None

Exploit likelihood

0.56%Down 0.5 points since Apr 14, 2021
90%50%10%1%

What each source reports

NVD Score used 7.4

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.

Record
CVE-2019-9803
CVSS 3.0
7.4 HighCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
CVSS 2.0
5.8 MediumAV:N/AC:M/Au:N/C:P/I:P/A:N
Weakness
CWE-346
Updated
2026-11-02
CVE List No score

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.

Record
CVE-2019-9803
Updated
2026-11-02
EUVDEUVD-2019-19165 No score

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.

Record
EUVD-2019-19165
Updated
2026-11-03
GitHub AdvisoriesGHSA-6h7p-w66v-f7vw 7.4

The Upgrade-Insecure-Requests (UIR) specification states that if UIR is enabled through Content...

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.

Record
GHSA-6h7p-w66v-f7vw
CVSS 3.0
7.4 HighCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Weakness
CWE-346
Updated
2026-11-02
OSVUBUNTU-CVE-2019-9803 7.4

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.

Record
UBUNTU-CVE-2019-9803
CVSS 3.0
7.4 HighCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Updated
2026-11-02
OSVopenSUSE-SU-2024:10600-1 No score

MozillaFirefox-92.0-1.2 on GA media

These are all security issues fixed in the MozillaFirefox-92.0-1.2 package on the GA media of openSUSE Tumbleweed.

Record
openSUSE-SU-2024:10600-1
Updated
2026-11-02
OSVopenSUSE-SU-2024:14572-1 No score

firefox-esr-128.5.1-1.1 on GA media

These are all security issues fixed in the firefox-esr-128.5.1-1.1 package on the GA media of openSUSE Tumbleweed.

Record
openSUSE-SU-2024:14572-1
Updated
2026-11-02
OSVUSN-3918-1 No score

firefox vulnerabilities

Multiple security issues were discovered in Firefox. If a user were tricked in to opening a specially crafted website, an attacker could potentially exploit these to cause a denial of service via application crash, denial of service via successive FTP authorization prompts or modal alerts, trick the user with confusing permission request prompts, obtain sensitive information, conduct social engineering attacks, or execute arbitrary code. (CVE-2019-9788, CVE-2019-9789, CVE-2019-9790, CVE-2019-9791, CVE-2019-9792, CVE-2019-9795, CVE-2019-9796, CVE-2019-9797, CVE-2019-9799, CVE-2019-9802, CVE-2019-9805, CVE-2019-9806, CVE-2019-9807, CVE-2019-9808, CVE-2019-9809)

A mechanism was discovered that removes some bounds checking for string, array, or typed array accesses if Spectre mitigations have been disabled. If a user were tricked in to opening a specially crafted website with Spectre mitigations disabled, an attacker could potentially exploit this to cause a denial of service, or execute arbitrary code. (CVE-2019-9793)

It was discovered that Upgrade-Insecure-Requests was incorrectly enforced for same-origin navigation. An attacker could potentially exploit this to conduct machine-in-the-middle (MITM) attacks. (CVE-2019-9803)

Record
USN-3918-1
Updated
2026-11-02
OSVUSN-3918-2 No score

firefox vulnerabilities

USN-3918-1 fixed vulnerabilities in Firefox. This update provides the corresponding updates for Ubuntu 14.04 LTS.

Original advisory details:

Multiple security issues were discovered in Firefox. If a user were tricked in to opening a specially crafted website, an attacker could potentially exploit these to cause a denial of service via application crash, denial of service via successive FTP authorization prompts or modal alerts, trick the user with confusing permission request prompts, obtain sensitive information, conduct social engineering attacks, or execute arbitrary code. (CVE-2019-9788, CVE-2019-9789, CVE-2019-9790, CVE-2019-9791, CVE-2019-9792, CVE-2019-9795, CVE-2019-9796, CVE-2019-9797, CVE-2019-9799, CVE-2019-9802, CVE-2019-9805, CVE-2019-9806, CVE-2019-9807, CVE-2019-9808, CVE-2019-9809)

A mechanism was discovered that removes some bounds checking for string, array, or typed array accesses if Spectre mitigations have been disabled. If a user were tricked in to opening a specially crafted website with Spectre mitigations disabled, an attacker could potentially exploit this to cause a denial of service, or execute arbitrary code. (CVE-2019-9793)

It was discovered that Upgrade-Insecure-Requests was incorrectly enforced for same-origin navigation. An attacker could potentially exploit this to conduct machine-in-the-middle (MITM) attacks. (CVE-2019-9803)

Record
USN-3918-2
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
firefox
Ubuntu:14.04:LTS
before 66.0.1+build1-0ubuntu0.14.04.1, plus listed versions
24.0+build1-0ubuntu125.0+build3-0ubuntu0.13.10.128.0~b2+build1-0ubuntu228.0+build1-0ubuntu128.0+build2-0ubuntu1
Show 45 moreShow less
28.0+build2-0ubuntu229.0+build1-0ubuntu0.14.04.230.0+build1-0ubuntu0.14.04.331.0+build1-0ubuntu0.14.04.132.0+build1-0ubuntu0.14.04.132.0.3+build1-0ubuntu0.14.04.133.0+build2-0ubuntu0.14.04.134.0+build2-0ubuntu0.14.04.135.0+build3-0ubuntu0.14.04.235.0.1+build1-0ubuntu0.14.04.136.0+build2-0ubuntu0.14.04.436.0.1+build2-0ubuntu0.14.04.136.0.4+build1-0ubuntu0.14.04.137.0+build2-0ubuntu0.14.04.137.0.1+build1-0ubuntu0.14.04.137.0.2+build1-0ubuntu0.14.04.138.0+build3-0ubuntu0.14.04.139.0+build5-0ubuntu0.14.04.139.0.3+build2-0ubuntu0.14.04.140.0+build4-0ubuntu0.14.04.140.0+build4-0ubuntu0.14.04.440.0.3+build1-0ubuntu0.14.04.141.0+build3-0ubuntu0.14.04.141.0.1+build2-0ubuntu0.14.04.141.0.2+build2-0ubuntu0.14.04.142.0+build2-0ubuntu0.14.04.143.0+build1-0ubuntu0.14.04.143.0.4+build3-0ubuntu0.14.04.144.0+build3-0ubuntu0.14.04.144.0.1+build2-0ubuntu0.14.04.144.0.2+build1-0ubuntu0.14.04.145.0+build2-0ubuntu0.14.04.145.0.1+build1-0ubuntu0.14.04.245.0.2+build1-0ubuntu0.14.04.146.0+build5-0ubuntu0.14.04.246.0.1+build1-0ubuntu0.14.04.347.0+build3-0ubuntu0.14.04.148.0+build2-0ubuntu0.14.04.149.0+build4-0ubuntu0.14.04.149.0.2+build2-0ubuntu0.14.04.150.0+build2-0ubuntu0.14.04.250.0.2+build1-0ubuntu0.14.04.150.1.0+build2-0ubuntu0.14.04.151.0.1+build2-0ubuntu0.14.04.151.0.1+build2-0ubuntu0.14.04.2
66.0.1+build1-0ubuntu0.14.04.1
firefox
Ubuntu:16.04:LTS
before 66.0+build3-0ubuntu0.16.04.2, plus listed versions
41.0.2+build2-0ubuntu142.0+build2-0ubuntu144.0+build3-0ubuntu244.0.1+build1-0ubuntu144.0.2+build1-0ubuntu1
Show 45 moreShow less
45.0+build2-0ubuntu145.0.1+build1-0ubuntu145.0.2+build1-0ubuntu146.0+build5-0ubuntu0.16.04.246.0.1+build1-0ubuntu0.16.04.247.0+build3-0ubuntu0.16.04.148.0+build2-0ubuntu0.16.04.149.0+build4-0ubuntu0.16.04.149.0.2+build2-0ubuntu0.16.04.250.0+build2-0ubuntu0.16.04.250.0.2+build1-0ubuntu0.16.04.150.1.0+build2-0ubuntu0.16.04.151.0.1+build2-0ubuntu0.16.04.151.0.1+build2-0ubuntu0.16.04.252.0+build2-0ubuntu0.16.04.152.0.1+build2-0ubuntu0.16.04.152.0.2+build1-0ubuntu0.16.04.153.0+build6-0ubuntu0.16.04.153.0.2+build1-0ubuntu0.16.04.253.0.3+build1-0ubuntu0.16.04.254.0+build3-0ubuntu0.16.04.155.0.1+build2-0ubuntu0.16.04.255.0.2+build1-0ubuntu0.16.04.156.0+build6-0ubuntu0.16.04.156.0+build6-0ubuntu0.16.04.257.0+build4-0ubuntu0.16.04.557.0+build4-0ubuntu0.16.04.657.0.1+build2-0ubuntu0.16.04.157.0.3+build1-0ubuntu0.16.04.157.0.4+build1-0ubuntu0.16.04.158.0+build6-0ubuntu0.16.04.158.0.1+build1-0ubuntu0.16.04.158.0.2+build1-0ubuntu0.16.04.159.0+build5-0ubuntu0.16.04.159.0.1+build1-0ubuntu0.16.04.159.0.2+build1-0ubuntu0.16.04.159.0.2+build1-0ubuntu0.16.04.360.0+build2-0ubuntu0.16.04.160.0.1+build2-0ubuntu0.16.04.160.0.2+build1-0ubuntu0.16.04.161.0+build3-0ubuntu0.16.04.261.0.1+build1-0ubuntu0.16.04.162.0+build2-0ubuntu0.16.04.362.0+build2-0ubuntu0.16.04.462.0+build2-0ubuntu0.16.04.5
66.0+build3-0ubuntu0.16.04.2
firefox
Ubuntu:18.04:LTS
before 66.0+build3-0ubuntu0.18.04.1, plus listed versions
56.0+build6-0ubuntu157.0.1+build2-0ubuntu159.0.1+build1-0ubuntu159.0.2+build1-0ubuntu160.0+build2-0ubuntu1
Show 13 moreShow less
60.0.1+build2-0ubuntu0.18.04.160.0.2+build1-0ubuntu0.18.04.161.0+build3-0ubuntu0.18.04.161.0.1+build1-0ubuntu0.18.04.162.0+build2-0ubuntu0.18.04.362.0+build2-0ubuntu0.18.04.462.0+build2-0ubuntu0.18.04.562.0.3+build1-0ubuntu0.18.04.163.0+build2-0ubuntu0.18.04.263.0.3+build1-0ubuntu0.18.04.164.0+build3-0ubuntu0.18.04.165.0+build2-0ubuntu0.18.04.165.0.1+build2-0ubuntu0.18.04.1
66.0+build3-0ubuntu0.18.04.1
mozjs52
Ubuntu:18.04:LTS
All versions, plus listed versions
52.3.1-0ubuntu352.3.1-7fakesync152.8.1-0ubuntu0.18.04.152.9.1-0ubuntu0.18.04.1
None known
mozjs38
Ubuntu:18.04:LTS
All versions, plus listed versions
38.8.0~repack1-0ubuntu138.8.0~repack1-0ubuntu338.8.0~repack1-0ubuntu4
None known
mozjs52
Ubuntu:20.04:LTS
All versions, plus listed versions
52.9.1-1build152.9.1-1ubuntu3
None known
firefox
Ubuntu:16.04:LTS
From an advisory covering 17 CVEs
before 66.0+build3-0ubuntu0.16.04.2, plus listed versions
41.0.2+build2-0ubuntu142.0+build2-0ubuntu144.0+build3-0ubuntu244.0.1+build1-0ubuntu144.0.2+build1-0ubuntu1
Show 45 moreShow less
45.0+build2-0ubuntu145.0.1+build1-0ubuntu145.0.2+build1-0ubuntu146.0+build5-0ubuntu0.16.04.246.0.1+build1-0ubuntu0.16.04.247.0+build3-0ubuntu0.16.04.148.0+build2-0ubuntu0.16.04.149.0+build4-0ubuntu0.16.04.149.0.2+build2-0ubuntu0.16.04.250.0+build2-0ubuntu0.16.04.250.0.2+build1-0ubuntu0.16.04.150.1.0+build2-0ubuntu0.16.04.151.0.1+build2-0ubuntu0.16.04.151.0.1+build2-0ubuntu0.16.04.252.0+build2-0ubuntu0.16.04.152.0.1+build2-0ubuntu0.16.04.152.0.2+build1-0ubuntu0.16.04.153.0+build6-0ubuntu0.16.04.153.0.2+build1-0ubuntu0.16.04.253.0.3+build1-0ubuntu0.16.04.254.0+build3-0ubuntu0.16.04.155.0.1+build2-0ubuntu0.16.04.255.0.2+build1-0ubuntu0.16.04.156.0+build6-0ubuntu0.16.04.156.0+build6-0ubuntu0.16.04.257.0+build4-0ubuntu0.16.04.557.0+build4-0ubuntu0.16.04.657.0.1+build2-0ubuntu0.16.04.157.0.3+build1-0ubuntu0.16.04.157.0.4+build1-0ubuntu0.16.04.158.0+build6-0ubuntu0.16.04.158.0.1+build1-0ubuntu0.16.04.158.0.2+build1-0ubuntu0.16.04.159.0+build5-0ubuntu0.16.04.159.0.1+build1-0ubuntu0.16.04.159.0.2+build1-0ubuntu0.16.04.159.0.2+build1-0ubuntu0.16.04.360.0+build2-0ubuntu0.16.04.160.0.1+build2-0ubuntu0.16.04.160.0.2+build1-0ubuntu0.16.04.161.0+build3-0ubuntu0.16.04.261.0.1+build1-0ubuntu0.16.04.162.0+build2-0ubuntu0.16.04.362.0+build2-0ubuntu0.16.04.462.0+build2-0ubuntu0.16.04.5
66.0+build3-0ubuntu0.16.04.2
firefox
Ubuntu:18.04:LTS
From an advisory covering 17 CVEs
before 66.0+build3-0ubuntu0.18.04.1, plus listed versions
56.0+build6-0ubuntu157.0.1+build2-0ubuntu159.0.1+build1-0ubuntu159.0.2+build1-0ubuntu160.0+build2-0ubuntu1
Show 13 moreShow less
60.0.1+build2-0ubuntu0.18.04.160.0.2+build1-0ubuntu0.18.04.161.0+build3-0ubuntu0.18.04.161.0.1+build1-0ubuntu0.18.04.162.0+build2-0ubuntu0.18.04.362.0+build2-0ubuntu0.18.04.462.0+build2-0ubuntu0.18.04.562.0.3+build1-0ubuntu0.18.04.163.0+build2-0ubuntu0.18.04.263.0.3+build1-0ubuntu0.18.04.164.0+build3-0ubuntu0.18.04.165.0+build2-0ubuntu0.18.04.165.0.1+build2-0ubuntu0.18.04.1
66.0+build3-0ubuntu0.18.04.1
firefox
Ubuntu:14.04:LTS
From an advisory covering 17 CVEs
before 66.0.1+build1-0ubuntu0.14.04.1, plus listed versions
24.0+build1-0ubuntu125.0+build3-0ubuntu0.13.10.128.0~b2+build1-0ubuntu228.0+build1-0ubuntu128.0+build2-0ubuntu1
Show 45 moreShow less
28.0+build2-0ubuntu229.0+build1-0ubuntu0.14.04.230.0+build1-0ubuntu0.14.04.331.0+build1-0ubuntu0.14.04.132.0+build1-0ubuntu0.14.04.132.0.3+build1-0ubuntu0.14.04.133.0+build2-0ubuntu0.14.04.134.0+build2-0ubuntu0.14.04.135.0+build3-0ubuntu0.14.04.235.0.1+build1-0ubuntu0.14.04.136.0+build2-0ubuntu0.14.04.436.0.1+build2-0ubuntu0.14.04.136.0.4+build1-0ubuntu0.14.04.137.0+build2-0ubuntu0.14.04.137.0.1+build1-0ubuntu0.14.04.137.0.2+build1-0ubuntu0.14.04.138.0+build3-0ubuntu0.14.04.139.0+build5-0ubuntu0.14.04.139.0.3+build2-0ubuntu0.14.04.140.0+build4-0ubuntu0.14.04.140.0+build4-0ubuntu0.14.04.440.0.3+build1-0ubuntu0.14.04.141.0+build3-0ubuntu0.14.04.141.0.1+build2-0ubuntu0.14.04.141.0.2+build2-0ubuntu0.14.04.142.0+build2-0ubuntu0.14.04.143.0+build1-0ubuntu0.14.04.143.0.4+build3-0ubuntu0.14.04.144.0+build3-0ubuntu0.14.04.144.0.1+build2-0ubuntu0.14.04.144.0.2+build1-0ubuntu0.14.04.145.0+build2-0ubuntu0.14.04.145.0.1+build1-0ubuntu0.14.04.245.0.2+build1-0ubuntu0.14.04.146.0+build5-0ubuntu0.14.04.246.0.1+build1-0ubuntu0.14.04.347.0+build3-0ubuntu0.14.04.148.0+build2-0ubuntu0.14.04.149.0+build4-0ubuntu0.14.04.149.0.2+build2-0ubuntu0.14.04.150.0+build2-0ubuntu0.14.04.250.0.2+build1-0ubuntu0.14.04.150.1.0+build2-0ubuntu0.14.04.151.0.1+build2-0ubuntu0.14.04.151.0.1+build2-0ubuntu0.14.04.2
66.0.1+build1-0ubuntu0.14.04.1
MozillaFirefox
openSUSE:Tumbleweed
From an advisory covering 661 CVEs
before 92.0-1.2
92.0-1.2
firefox-esr
openSUSE:Tumbleweed
From an advisory covering 1860 CVEs
before 128.5.1-1.1
128.5.1-1.1

History

History
RecordedChangedSources
affected, facts
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2019-9803 is a high vulnerability (CVSS 7.4) in Mozilla Firefox, published March 20, 2019. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.56%, the 46th percentile. Fixed in firefox 66.0.1+build1-0ubuntu0.14.04.1.

References

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