The Firefox and Firefox Focus UI for the Android custom tab feature only showed the "site" that was loaded, not the full hostname. User supplied content hosted on a subdomain of a site could have been used to fool a user into thinking it was content from a different subdomain of that site. This vulnerability was fixed in Firefox 144.
Conclusion & alert: CVE-2025-11720 is rated Low Risk (36.3/100): CVSS High severity, with low exploitation likelihood (EPSS 0.04%). Mandatory action: Monitor for updates and reassess as exploit intelligence or EPSS changes.
Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.
EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).
| # | Date | Old EPSS score | New EPSS score | Delta (New - Old) |
|---|---|---|---|---|
| 1 | 2026-03-12 | 0.05% | 0.04% | -0.02% |
| 2 | 2025-12-21 | 0.02% | 0.05% | +0.04% |
| 3 | 2025-10-15 | — | 0.02% | — |
Full EPSS history (3 records total)
CVSS metrics for this CVE.
| Base score | Version | Severity | Vector | Exploitability | Impact | Score source |
|---|---|---|---|---|---|---|
| 8.1 | 3.1 | HIGH |
|
2.8 | 5.2 | [email protected] |
| 8.1 | 3.1 | HIGH |
|
2.8 | 5.2 | 134c704f-9b21-4f2e-91b3-4a467353bcc0 |
| vendor | priority | summary | link |
|---|---|---|---|
alpine
|
— | CVE-2025-11720: 1 source package rows (firefox); 160 state rows across 2 repos (3.22-community, edge-community); fixed 0, open 160. | https://security.alpinelinux.org/vuln/CVE-2025-11720 |
debian
|
unimportant | CVE-2025-11720 unimportant priority: Debian including 1 source packages (firefox), 1 status rows across 1 suites (sid): resolved 1. | https://security-tracker.debian.org/tracker/CVE-2025-11720 |
ubuntu
|
medium | CVE-2025-11720 medium priority: Ubuntu including 9 source packages (firefox, mozjs102, …), 49 status rows across 7 suites (bionic, focal, jammy, noble, plucky, questing, upstream): DNE 22, ignored 9, needs-triage 9, not-affected 9. | https://ubuntu.com/security/CVE-2025-11720 |
| URL | Tags |
|---|---|
| https://bugzilla.mozilla.org/show_bug.cgi?id=1979534 | Issue Tracking Permissions Required |
| https://bugzilla.mozilla.org/show_bug.cgi?id=1984370 | Issue Tracking Permissions Required |
| https://www.mozilla.org/security/advisories/mfsa2025-81/ | Vendor Advisory |