Summary
Multiple security issues were discovered in Firefox. If a user were
tricked into opening a specially crafted website, an attacker could
potentially exploit these to cause a denial of service, obtain sensitive
information across domains, or execute arbitrary code. (CVE-2025-1011,
CVE-2025-1013, CVE-2025-1014, CVE-2025-1016, CVE-2025-1017, CVE-2025-1018,
CVE-2025-1019, CVE-2025-1020)
Ivan Fratric discovered that Firefox did not properly handle XSLT data,
leading to a use-after-free vulnerability. An attacker could potentially
exploit this issue to cause a denial of service, or execute arbitrary code.
(CVE-2025-1009)
Atte Kettunen discovered that Firefox did not properly manage memory in
the Custom Highlight API, leading to a use-after-free vulnerability. An
attacker could potentially exploit this issue to cause a denial of service,
or execute arbitrary code. (CVE-2025-1010)
Nils Bars discovered that Firefox did not properly manage memory during
concurrent delazification, leading to a use-after-free vulnerability.
An attacker could potentially exploit this issue to cause a denial of
service, or execute arbitrary code. (CVE-2025-1012)
Fixed packages 1
| Release | Package | Fixed in |
|---|---|---|
| Ubuntu · 20.04 LTS 20.04:LTS | firefox | 135.0+build2-0ubuntu0.20.04.1 |
Vulnerabilities 11
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Critical 9.8
Use-after-free in XSLT
An attacker could have caused a use-after-free via crafted XSLT data, leading to a potentially exploitable crash. This vulnerability was fixed in Firefox 135, Firefox ESR 115.20, Firefox ESR 128.7, Thunderbird 128.7, and Thunderbird 135.
-
Critical 9.8
Use-after-free in Custom Highlight
An attacker could have caused a use-after-free via the Custom Highlight API, leading to a potentially exploitable crash. This vulnerability was fixed in Firefox 135, Firefox ESR 115.20, Firefox ESR 128.7, Thunderbird 128.7, and Thunderbird 135.
-
Critical 9.8
A bug in WebAssembly code generation could result in a crash
A bug in WebAssembly code generation could have lead to a crash. It may have been possible for an attacker to leverage this to achieve code execution. This vulnerability was fixed in Firefox 135, Firefox ESR 128.7, Thunderbird 128.7, and Thunderbird 135.
-
Critical 9.8
Use-after-free during concurrent delazification
A race during concurrent delazification could have led to a use-after-free. This vulnerability was fixed in Firefox 135, Firefox ESR 115.20, Firefox ESR 128.7, Thunderbird 128.7, and Thunderbird 135.
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Critical 9.8
Memory safety bugs fixed in Firefox 135, Thunderbird 135, Firefox ESR 115.20, Firefox ESR 128.7, Thunderbird 115.20, and Thunderbird 128.7
Memory safety bugs present in Firefox 134, Thunderbird 134, Firefox ESR 115.19, Firefox ESR 128.6, Thunderbird 115.19, and Thunderbird 128.6. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could ha…
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Critical 9.8
Memory safety bugs fixed in Firefox 135, Thunderbird 135, Firefox ESR 128.7, and Thunderbird 128.7
Memory safety bugs present in Firefox 134, Thunderbird 134, Firefox ESR 128.6, and Thunderbird 128.6. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code.…
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Critical 9.8
Memory safety bugs fixed in Firefox 135 and Thunderbird 135
Memory safety bugs present in Firefox 134 and Thunderbird 134. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefo…
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High 8.8
Certificate length was not properly checked
Certificate length was not properly checked when added to a certificate store. In practice only trusted data was processed. This vulnerability was fixed in Firefox 135, Firefox ESR 128.7, Thunderbird 128.7, and Thunderbird 135.
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High 7.3
Fullscreen notification is not displayed when fullscreen is re-requested
The fullscreen notification is prematurely hidden when fullscreen is re-requested quickly by the user. This could have been leveraged to perform a potential spoofing attack. This vulnerability was fixed in Firefox 135 and Thunderbird 135.
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Medium 6.5
Potential opening of private browsing tabs in normal browsing windows
A race condition could have led to private browsing tabs being opened in normal browsing windows. This could have resulted in a potential privacy leak. This vulnerability was fixed in Firefox 135, Firefox ESR 128.7, Thunderbird 128.7, and Thunderbird 135.
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Medium 4.3
Fullscreen notification not properly displayed
The z-order of the browser windows could be manipulated to hide the fullscreen notification. This could potentially be leveraged to perform a spoofing attack. This vulnerability was fixed in Firefox 135 and Thunderbird 135.
References
-
report
https://ubuntu.com/security/CVE-2025-1009
-
report
https://ubuntu.com/security/CVE-2025-1010
-
report
https://ubuntu.com/security/CVE-2025-1011
-
report
https://ubuntu.com/security/CVE-2025-1012
-
report
https://ubuntu.com/security/CVE-2025-1013
-
report
https://ubuntu.com/security/CVE-2025-1014
-
report
https://ubuntu.com/security/CVE-2025-1016
-
report
https://ubuntu.com/security/CVE-2025-1017
-
report
https://ubuntu.com/security/CVE-2025-1018
-
report
https://ubuntu.com/security/CVE-2025-1019
-
report
https://ubuntu.com/security/CVE-2025-1020