SB2026011359 - Multiple vulnerabilities in Mozilla Firefox

Description

This security bulletin contains information about 16 vulnerabilities.

1) Buffer overflow (CVE-ID: CVE-2026-0886)

CWE-ID: CWE-119 - Memory corruption

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

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to a boundary error in the Graphics component. A remote attacker can create a specially crafted website, trick the victim into opening it, trigger memory corruption and execute arbitrary code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

2) Buffer overflow (CVE-ID: CVE-2026-0891)

CWE-ID: CWE-119 - Memory corruption

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

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to a boundary error when processing HTML content. A remote attacker can create a specially crafted website, trick the victim into opening it, trigger memory corruption and execute arbitrary code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

3) Spoofing attack (CVE-ID: CVE-2026-0890)

CWE-ID: CWE-451 - User Interface (UI) Misrepresentation of Critical Information (Clickjacking, spoofing)

CVSSv4: CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:A/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear

The vulnerability allows a remote attacker to perform spoofing attack.

The vulnerability exists due to incorrect processing of user-supplied data in the DOM: Copy & Paste and Drag & Drop component. A remote attacker can spoof page content.

4) Improper Restriction of Rendered UI Layers or Frames (CVE-ID: CVE-2026-0887)

CWE-ID: CWE-1021 - Improper Restriction of Rendered UI Layers or Frames

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

The vulnerability allows a remote attacker to perform clickjacking attacks.

The vulnerability exists due to an error in the PDF Viewer. A remote attacker can trick the victim into opening a specially crafted URL and gain access to sensitive information or perform clickjacking attack.

5) Use-after-free (CVE-ID: CVE-2026-0885)

CWE-ID: CWE-416 - Use After Free

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/U:Clear

The vulnerability allows a remote attacker to perform a denial of service attack.

The vulnerability exists due to a use-after-free error in the JavaScript: GC component. A remote attacker can trick the victim into visiting a specially crafted website and crash the browser.

6) Protection mechanism failure (CVE-ID: CVE-2026-0877)

CWE-ID: CWE-693 - Protection Mechanism Failure

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

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

The vulnerability exists due to insufficient implementation of security measures. An attacker can bypass implemented DOM security restrictions and execute arbitrary JavaScript code.

7) Use-after-free (CVE-ID: CVE-2026-0884)

CWE-ID: CWE-416 - Use After Free

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/U:Clear

The vulnerability allows a remote attacker to perform a denial of service attack.

The vulnerability exists due to a use-after-free error in the JavaScript Engine component. A remote attacker can trick the victim into visiting a specially crafted website and crash the browser.

8) Information disclosure (CVE-ID: CVE-2026-0883)

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

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

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

The vulnerability exists due to excessive data output by the Networking component. A remote attacker can gain unauthorized access to sensitive information on the system.

9) Use-after-free (CVE-ID: CVE-2026-0882)

CWE-ID: CWE-416 - Use After Free

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

The vulnerability allows a remote attacker to compromise vulnerable system.

The vulnerability exists due to a use-after-free error in the IPC component. A remote attacker can trick the victim into visiting a specially crafted web page and execute arbitrary code on the system.

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

10) Integer overflow (CVE-ID: CVE-2026-0880)

CWE-ID: CWE-190 - Integer overflow

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

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to integer overflow in the Graphics component. A remote attacker can trick the victim into visiting a specially crafted website, trigger an integer overflow and execute arbitrary code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

11) Buffer overflow (CVE-ID: CVE-2026-0879)

CWE-ID: CWE-119 - Memory corruption

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

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to a boundary error in the Graphics component. A remote attacker can create a specially crafted website, trick the victim into opening it, trigger memory corruption and execute arbitrary code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

12) Buffer overflow (CVE-ID: CVE-2026-0878)

CWE-ID: CWE-119 - Memory corruption

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

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to a boundary error within the in the Graphics: CanvasWebGL component. A remote attacker can trick the victim into visiting a specially crafted website, trigger memory corruption and execute arbitrary code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

13) Protection mechanism failure (CVE-ID: CVE-2026-0881)

CWE-ID: CWE-693 - Protection Mechanism Failure

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

The vulnerability allows a remote attacker to compromise the affected system.

The vulnerability exists due to insufficient implementation of security measures in the Messaging System component. A remote attacker can bypass implemented sandbox restrictions and compromise the affected system.

14) Information disclosure (CVE-ID: CVE-2026-0888)

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

CVSSv4: CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:N/SA:N/E:U/U:Clear

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

The vulnerability exists due to excessive data output by the application in the XML component. A remote attacker can gain unauthorized access to sensitive information on the system.

15) Input validation error (CVE-ID: CVE-2026-0889)

CWE-ID: CWE-20 - Improper input validation

CVSSv4: CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/U:Clear

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to insufficient validation of user-supplied input in the DOM: Service Workers component. A remote attacker can perform a denial of service attack.

16) Buffer overflow (CVE-ID: CVE-2026-0892)

CWE-ID: CWE-119 - Memory corruption

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

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to a boundary error when processing HTML content. A remote attacker can create a specially crafted website, trick the victim into opening it, trigger memory corruption and execute arbitrary code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

Remediation

Install update from vendor's website.

References

• https://www.mozilla.org/en-US/security/advisories/mfsa2026-02/
• https://www.mozilla.org/en-US/security/advisories/mfsa2026-01/
• https://www.mozilla.org/en-US/security/advisories/mfsa2026-03/