CVE-2025-6431 | The prompt in Firefox for Android that asks before opening a link in an external application could be bypassed

When a link can be opened in an external application, Firefox for Android will, by default, prompt the user before doing so. An attacker could have bypassed this prompt, potentially exposing the user to security vulnerabilities or privacy leaks in external applications. *This bug only affects Firefox for Android. Other versions of Firefox are unaffected.*. This vulnerability was fixed in Firefox 140.

Published: 2025-06-24 Last update: 2026-04-13 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2025-6431 is rated Moderate Risk (40/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.18%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2025-6431

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 2026-04-20 0.05% 0.18% +0.13%
2 2026-04-10 0.03% 0.05% +0.03%
3 2025-11-21 — 0.03% —

Full EPSS history (5 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-6431

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.5 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 2.8 3.6 134c704f-9b21-4f2e-91b3-4a467353bcc0

Weakness enumeration for CVE-2025-6431

OS Trackers for CVE-2025-6431

vendor priority summary link
alpine — CVE-2025-6431: 1 source package rows (firefox); 148 state rows across 2 repos (3.22-community, edge-community); fixed 0, open 148. https://security.alpinelinux.org/vuln/CVE-2025-6431
debian unimportant CVE-2025-6431 unimportant priority: Debian including 1 source packages (firefox), 1 status rows across 1 suites (sid): resolved 1. https://security-tracker.debian.org/tracker/CVE-2025-6431
redhat low — https://access.redhat.com/security/cve/CVE-2025-6431
suse high CVE-2025-6431 severity important: SUSE including 61 source package names (MozillaFirefox-140.0-112.270.2, MozillaFirefox-140.0.2-1.1, …), 321 product×package rows across 40 product lines (Image SLES12-SP5-SAP-Azure-LI-BYOS-Production, Image SLES12-SP5-SAP-Azure-VLI-BYOS-Production, … (40 product lines)): Fixed 321. https://www.suse.com/security/cve/CVE-2025-6431/
ubuntu medium CVE-2025-6431 medium priority: Ubuntu including 9 source packages (firefox, mozjs102, …), 58 status rows across 8 suites (bionic, focal, jammy, noble, oracular, plucky, questing, upstream): DNE 28, not-affected 11, ignored 10, needs-triage 9. https://ubuntu.com/security/CVE-2025-6431

Affected software / configurations for CVE-2025-6431

Vendor Product Version Raw CPE
mozilla firefox < 140.0 cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:*

References for CVE-2025-6431

cvelogic Threat Intelligence