Mozilla: >> Firefox >> 153.2.0 Security Vulnerabilities
Internally found bugs present in Thunderbird 154. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 155 and Thunderbird 155.
CVSS Score
9.8
EPSS Score
0.006
Published
2026-09-01
Denial-of-service in the PDF Viewer component. This vulnerability was fixed in Firefox 155 and Thunderbird 155.
CVSS Score
6.5
EPSS Score
0.004
Published
2026-09-01
Incorrect boundary conditions in the Layout: Grid component. This vulnerability was fixed in Firefox 155 and Thunderbird 155.
CVSS Score
4.3
EPSS Score
0.003
Published
2026-09-01
Privilege escalation in the WebDriver BiDi component. This vulnerability was fixed in Firefox 155 and Thunderbird 155.
CVSS Score
8.8
EPSS Score
0.004
Published
2026-09-01
Sandbox escape in the Remote Settings Client component. This vulnerability was fixed in Firefox 154, Thunderbird 154, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 140.15, and Thunderbird 153.2.
CVSS Score
10.0
EPSS Score
0.005
Published
2026-08-18
Internally found bugs present in Thunderbird 153. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 154 and Thunderbird 154.
CVSS Score
9.8
EPSS Score
0.006
Published
2026-08-18
Use-after-free in the Graphics: Text component. This vulnerability was fixed in Firefox 154, Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
CVSS Score
9.8
EPSS Score
0.006
Published
2026-08-18
The HTTP/2 protocol does not consider the role of the TCP congestion window in providing information about content length, which makes it easier for remote attackers to obtain cleartext data by leveraging a web-browser configuration in which third-party cookies are sent, aka a "HEIST" attack.
CVSS Score
5.3
EPSS Score
0.14
Published
2016-09-06
The HTTPS protocol does not consider the role of the TCP congestion window in providing information about content length, which makes it easier for remote attackers to obtain cleartext data by leveraging a web-browser configuration in which third-party cookies are sent, aka a "HEIST" attack.
CVSS Score
5.3
EPSS Score
0.14
Published
2016-09-06
Cross-site scripting (XSS) vulnerability in clickstream.js in Y! Toolbar plugin for FireFox 3.1.0.20130813024103 for Mac, and 2.5.9.2013418100420 for Windows, allows remote attackers to inject arbitrary web script or HTML via a crafted URL that is stored by the victim.
CVSS Score
4.3
EPSS Score
0.019
Published
2014-01-26
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