CVE-2019-9803
The Upgrade-Insecure-Requests (UIR) specification states that if UIR is enabled through Content Security Policy (CSP), navigation to a…
- 7.4HighCVSS base score
- 0.56%Exploitation in 30 daysEPSS · top 53% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
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.
Timeline
ID reserved
By mozilla
- 43 days later
· 43 days later
Published
- 5 years later
· 5 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| NVDNVD · Modified | 3.0 | High7.4 | CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N |
- EPSS (exploitation in 30 days)
- 0.56% · top 53% of all CVEs (11 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.4.
Affected products
References
References4
- https://www.mozilla.org/security/advisories/mfsa2019-07/ (opens in a new tab)x_refsource_MISCx_transferred
- https://bugzilla.mozilla.org/show_bug.cgi?id=1515863 (opens in a new tab)x_refsource_MISCx_transferred
- https://bugzilla.mozilla.org/show_bug.cgi?id=1437009 (opens in a new tab)x_refsource_MISCx_transferred
- https://w3c.github.io/webappsec-upgrade-insecure-requests/ (opens in a new tab)x_refsource_MISCx_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2019-19165 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2019-9803)Record last updated .