Exploited. On CISA's list since 2022-03-28.
Mozilla Firefox and Thunderbird Denial-of-Service Vulnerability
CVE-2013-1690 · Mozilla Firefox and Thunderbird · Published 2013-06-26
How bad would it be?
8.8 out of 10
CVSS rates it high.
How likely is it to be used?
69%
Estimated chance of exploitation in the next 30 days, among the top 1% of all scored flaws (EPSS, 2026-10-29).
Is it already being used?
Yes
CISA has seen it exploited in real attacks. For US government agencies the fix is deadline passed 1656 days ago (2022-04-18).
What CISA says to do
Apply updates per vendor instructions.
Mozilla Firefox and Thunderbird do not properly handle onreadystatechange events in conjunction with page reloading, which allows remote attackers to cause a denial-of-service (DoS) or possibly execute malicious code via a crafted web site.
What the flaw is
Mozilla Firefox before 22.0, Firefox ESR 17.x before 17.0.7, Thunderbird before 17.0.7, and Thunderbird ESR 17.x before 17.0.7 do not properly handle onreadystatechange events in conjunction with page reloading, which allows remote attackers to cause a denial of service (application crash) or possibly execute arbitrary code via a crafted web site that triggers an attempt to execute data at an unmapped memory location.
From the NVD.
Fixes and advisories
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Understand the kind of weakness behind this flaw. These resources teach the weakness, rather than reproduce this specific CVE. Follow the vendor's advice above to fix the affected product.
CWE-119 · CISA KEV; NVD record: 134c704f-9b21-4f2e-91b3-4a467353bcc0; NVD record: nvd@nist.gov. We have not selected a close learning match for this label.
CWE is a catalogue of weakness types. Labels come from the sources shown and can differ or change. Resource matches reviewed 16 October 2026.
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Exploited flaws from CISA's KEV catalogue. Chance of exploitation from EPSS by FIRST. Descriptions and scores from the NVD. This product uses the NVD API but is not endorsed or certified by the NVD.