Debian update for firefox-esr



Risk High
Patch available YES
Number of vulnerabilities 4
CVE-ID CVE-2025-6424
CVE-2025-6425
CVE-2025-6429
CVE-2025-6430
CWE-ID CWE-416
CWE-200
CWE-20
CWE-693
Exploitation vector Network
Public exploit N/A
Vulnerable software
 Debian Linux
Operating systems & Components / Operating system

firefox-esr (Debian package)
Operating systems & Components / Operating system package or component

Vendor Debian

Security Bulletin

This security bulletin contains information about 4 vulnerabilities.

1) Use-after-free

EUVDB-ID: #VU111885

Risk: High

CVSSv4.0: 5.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber]

CVE-ID: CVE-2025-6424

CWE-ID: CWE-416 - Use After Free

Exploit availability: No

Description

The vulnerability allows a remote attacker to compromise vulnerable system.

The vulnerability exists due to a use-after-free error in FontFaceSet. A remote attacker can trick the victim into opening a specially crafted website and execute arbitrary code on the system.

Successful exploitation of the vulnerability may allow an attacker to compromise vulnerable system.

Mitigation

Update firefox-esr package to version 128.12.0esr-1~deb12u1.

Vulnerable software versions

Debian Linux: All versions

firefox-esr (Debian package): before 128.12.0esr-1~deb12u1

CPE2.3 External links

https://lists.debian.org/debian-security-announce/2025/msg00114.html


Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.

2) Information disclosure

EUVDB-ID: #VU111886

Risk: Medium

CVSSv4.0: 1.2 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2025-6425

CWE-ID: CWE-200 - Exposure of sensitive information to an unauthorized actor

Exploit availability: No

Description

The vulnerability allows a remote attacker to gain access to potentially sensitive information.

The vulnerability exists due to the WebCompat extension shipped with Firefox allows to enumerate resources and obtain a persistent UUID that identifies the browser, and persists between containers and normal/private browsing mode, but not profiles.

Mitigation

Update firefox-esr package to version 128.12.0esr-1~deb12u1.

Vulnerable software versions

Debian Linux: All versions

firefox-esr (Debian package): before 128.12.0esr-1~deb12u1

CPE2.3 External links

https://lists.debian.org/debian-security-announce/2025/msg00114.html


Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.

3) Input validation error

EUVDB-ID: #VU111888

Risk: Low

CVSSv4.0: 0.5 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:U/U:Clear]

CVE-ID: CVE-2025-6429

CWE-ID: CWE-20 - Improper input validation

Exploit availability: No

Description

The vulnerability allows a remote attacker to bypass implemented security restrictions.

The vulnerability exists due to incorrect parsing of embedded URLs that led to URLs being rewritten to the youtube.com domain. A remote attacker can use a specially crafted embed tag to bypass website security checks that restricted which domains users were allowed to embed.

Mitigation

Update firefox-esr package to version 128.12.0esr-1~deb12u1.

Vulnerable software versions

Debian Linux: All versions

firefox-esr (Debian package): before 128.12.0esr-1~deb12u1

CPE2.3 External links

https://lists.debian.org/debian-security-announce/2025/msg00114.html


Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.

4) Protection Mechanism Failure

EUVDB-ID: #VU111889

Risk: Medium

CVSSv4.0: 1.2 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:U/U:Green]

CVE-ID: CVE-2025-6430

CWE-ID: CWE-693 - Protection Mechanism Failure

Exploit availability: No

Description

The vulnerability allows a remote attacker to bypass implemented security restrictions.

The vulnerability exists due to an error when handling embed or object tags. When a file download is specified via the Content-Disposition header, that directive would be ignored if the file was included via a <embed> or <object> tag, potentially making a website vulnerable to a cross-site scripting attack.

Mitigation

Update firefox-esr package to version 128.12.0esr-1~deb12u1.

Vulnerable software versions

Debian Linux: All versions

firefox-esr (Debian package): before 128.12.0esr-1~deb12u1

CPE2.3 External links

https://lists.debian.org/debian-security-announce/2025/msg00114.html


Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.



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