Is CVE-2012-4207 in the CISA KEV catalog?

No. CVE-2012-4207 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2012-4207?

CVE-2012-4207 has a CVSS v2 base score of 4.3 (MEDIUM).

What is the EPSS score for CVE-2012-4207?

CVE-2012-4207 has an EPSS score of 2.78% (85th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2012-4207?

Upgrade DeveloperEdition to 17.0 or later. Fixes are available for 3 affected products.

CVE & CISA-KEV Catalog

CVE-2012-4207

MEDIUMEPSS 85th pctl

4.3

CVSS v2

NVD

Description

The HZ-GB-2312 character-set implementation in Mozilla Firefox before 17.0, Firefox ESR 10.x before 10.0.11, Thunderbird before 17.0, Thunderbird ESR 10.x before 10.0.11, and SeaMonkey before 2.14 does not properly handle a ~ (tilde) character in proximity to a chunk delimiter, which allows remote attackers to conduct cross-site scripting (XSS) attacks via a crafted document.

CWE-79Cross-Site Scripting (XSS)

How to fix

Remediation Available

DeveloperEditionWindows application

Affected:17.0Fixed in:17.0Mozilla

Affected:10.0 10.0.11Fixed in:10.0.11Mozilla

Mozilla Firefox (en-US)Windows application

Affected:10.0 10.0.11Fixed in:10.0.11Mozilla

Affected:17.0Fixed in:17.0Mozilla

Mozilla Thunderbird (en-US)Windows application

Affected:17.0Fixed in:17.0Mozilla

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v2 Vector

No CVSS vector data available.

Exploit Intelligence

2.78%probability of exploitation in 30 days

85thpercentile

Elevated risk: more likely to be exploited than 85% of all known CVEs.

References

Related Vulnerabilities

Other CWE-79 (Cross-Site Scripting (XSS)) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2020-11022	Medium	6.9	99%	-	Fix
CVE-2019-3929	Critical	9.8	99%	KEV	Fix
CVE-2020-9496	Medium	6.1	99%	-	-
CVE-2023-28341	Medium	6.1	99%	-	Fix
CVE-2018-12998	Medium	6.1	98%	-	-
CVE-2025-4123	High	7.6	98%	-	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-04-29.