Mozilla Firefox and Thunderbird 1.x before 1.5 and 1.0.x before 1.0.8, Mozilla Suite before 1.7.13, and SeaMonkey before 1.0 returns the Object class prototype instead of the global window object when (1) .valueOf.call or (2) .valueOf.apply are called without any arguments, which allows remote attackers to conduct cross-site scripting (XSS) attacks.
Conclusion & alert: CVE-2006-1731 is rated Moderate Risk (42.5/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 1.78%). Mandatory action: Review affected assets and schedule remediation.
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 | 2026-06-15 | 2.82% | 1.78% | -1.04% |
| 2 | 2025-05-08 | 2.71% | 2.82% | +0.10% |
| 3 | 2025-03-30 | — | 2.71% | — |
Full EPSS history (12 records total)
CVSS metrics for this CVE.
| Base score | Version | Severity | Vector | Exploitability | Impact | Score source |
|---|---|---|---|---|---|---|
| 4.3 | 2.0 | MEDIUM |
|
8.6 | 2.9 | [email protected] |
| vendor | priority | summary | link |
|---|---|---|---|
debian
|
medium | CVE-2006-1731 medium priority: Debian including 2 source packages (firefox, thunderbird), 6 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 6. | https://security-tracker.debian.org/tracker/CVE-2006-1731 |
gentoo
|
normal | CVE-2006-1731: 3 GLSA(s) (200604-12, 200604-18, 200605-09), 6 atom(s) (mail-client/mozilla-thunderbird, mail-client/mozilla-thunderbird-bin, www-client/mozilla, www-client/mozilla-bin, www-client/mozilla-firefox, www-client/mozilla-firefox-bin); latest impact normal. | https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2006-1731 |
redhat
|
medium | — | https://access.redhat.com/security/cve/CVE-2006-1731 |
ubuntu
|
medium | CVE-2006-1731 medium priority: Ubuntu including 5 source packages (firefox, firefox-granparadiso, lightning-sunbird, midbrowser, mozilla-thunderbird), 20 status rows across 4 suites (dapper, edgy, feisty, upstream): DNE 9, needs-triage 5, released 4, not-affected 2. | https://ubuntu.com/security/CVE-2006-1731 |
: Fixed in: Firefox 1.5 Firefox 1.0.8 Thunderbird 1.5 Thunderbird 1.0.8 SeaMonkey 1.0 Mozilla Suite 1.7.13
| Vendor | Product | Version | Raw CPE |
|---|---|---|---|
| mozilla | firefox | <= 1.0.7 | cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* |
| mozilla | firefox | 1.0 | cpe:2.3:a:mozilla:firefox:1.0:*:*:*:*:*:*:* |
| mozilla | firefox | 1.0.1 | cpe:2.3:a:mozilla:firefox:1.0.1:*:*:*:*:*:*:* |
| mozilla | firefox | 1.0.2 | cpe:2.3:a:mozilla:firefox:1.0.2:*:*:*:*:*:*:* |
| mozilla | firefox | 1.0.3 | cpe:2.3:a:mozilla:firefox:1.0.3:*:*:*:*:*:*:* |
| mozilla | firefox | 1.0.4 | cpe:2.3:a:mozilla:firefox:1.0.4:*:*:*:*:*:*:* |
| mozilla | firefox | 1.0.5 | cpe:2.3:a:mozilla:firefox:1.0.5:*:*:*:*:*:*:* |
| mozilla | firefox | 1.0.6 | cpe:2.3:a:mozilla:firefox:1.0.6:*:*:*:*:*:*:* |
| mozilla | firefox | 1.5 | cpe:2.3:a:mozilla:firefox:1.5:*:*:*:*:*:*:* |
| mozilla | firefox | 1.5 | cpe:2.3:a:mozilla:firefox:1.5:beta1:*:*:*:*:*:* |
| mozilla | firefox | 1.5 | cpe:2.3:a:mozilla:firefox:1.5:beta2:*:*:*:*:*:* |
| mozilla | mozilla_suite | <= 1.7.12 | cpe:2.3:a:mozilla:mozilla_suite:*:*:*:*:*:*:*:* |
| mozilla | mozilla_suite | 1.7.6 | cpe:2.3:a:mozilla:mozilla_suite:1.7.6:*:*:*:*:*:*:* |
| mozilla | mozilla_suite | 1.7.7 | cpe:2.3:a:mozilla:mozilla_suite:1.7.7:*:*:*:*:*:*:* |
| mozilla | mozilla_suite | 1.7.8 | cpe:2.3:a:mozilla:mozilla_suite:1.7.8:*:*:*:*:*:*:* |
| mozilla | mozilla_suite | 1.7.10 | cpe:2.3:a:mozilla:mozilla_suite:1.7.10:*:*:*:*:*:*:* |
| mozilla | mozilla_suite | 1.7.11 | cpe:2.3:a:mozilla:mozilla_suite:1.7.11:*:*:*:*:*:*:* |
| mozilla | seamonkey | <= 1.0 | cpe:2.3:a:mozilla:seamonkey:*:beta:*:*:*:*:*:* |
| mozilla | seamonkey | 1.0 | cpe:2.3:a:mozilla:seamonkey:1.0:*:alpha:*:*:*:*:* |
| mozilla | thunderbird | <= 1.0.7 | cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* |
| mozilla | thunderbird | 1.0 | cpe:2.3:a:mozilla:thunderbird:1.0:*:*:*:*:*:*:* |
| mozilla | thunderbird | 1.0.1 | cpe:2.3:a:mozilla:thunderbird:1.0.1:*:*:*:*:*:*:* |
| mozilla | thunderbird | 1.0.2 | cpe:2.3:a:mozilla:thunderbird:1.0.2:*:*:*:*:*:*:* |
| mozilla | thunderbird | 1.0.3 | cpe:2.3:a:mozilla:thunderbird:1.0.3:*:*:*:*:*:*:* |
| mozilla | thunderbird | 1.0.4 | cpe:2.3:a:mozilla:thunderbird:1.0.4:*:*:*:*:*:*:* |
| mozilla | thunderbird | 1.0.5 | cpe:2.3:a:mozilla:thunderbird:1.0.5:*:*:*:*:*:*:* |
| mozilla | thunderbird | 1.0.5 | cpe:2.3:a:mozilla:thunderbird:1.0.5:beta:*:*:*:*:*:* |
| mozilla | thunderbird | 1.0.6 | cpe:2.3:a:mozilla:thunderbird:1.0.6:*:*:*:*:*:*:* |
| mozilla | thunderbird | 1.5 | cpe:2.3:a:mozilla:thunderbird:1.5:*:*:*:*:*:*:* |
| mozilla | thunderbird | 1.5 | cpe:2.3:a:mozilla:thunderbird:1.5:beta2:*:*:*:*:*:* |