Multiple vulnerabilities in Mozilla Thunderbird ESR

1) Double free

EUVDB-ID: #VU109855

Risk: High

CVSSv4.0: 6.1 [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]

CVE-ID: CVE-2025-5262

CWE-ID: CWE-415 - Double Free

Exploit availability: No

Description

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

The vulnerability exists due to a boundary error within the vpx_codec_enc_init_multi() function in libvpx encoder for WebRTC. A remote attacker can trick the victim into visiting a specially crafted website, trigger a double free error and execute arbitrary code on the target system.

Mitigation

Install update from vendor's website.

Vulnerable software versions

Mozilla Thunderbird: 128.0 - 128.10.2

CPE2.3

External links

https://www.mozilla.org/en-US/security/advisories/mfsa2025-46/

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.

2) Improper error handling

EUVDB-ID: #VU109857

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:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2025-5263

CWE-ID: CWE-388 - Error Handling

Exploit availability: No

Description

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

The vulnerability exists due to error handling for script execution is not correctly isolated from the web content. A remote attacker can trick the victim into opening a specially crafted website and obtain certain information cross-origin.

Mitigation

Install update from vendor's website.

Vulnerable software versions

Mozilla Thunderbird: 128.0 - 128.10.2

CPE2.3

External links

https://www.mozilla.org/en-US/security/advisories/mfsa2025-46/

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: #VU109858

Risk: Medium

CVSSv4.0: 4.5 [CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2025-5264

CWE-ID: CWE-20 - Improper input validation

Exploit availability: No

Description

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

The vulnerability exists due to insufficient validation of user-supplied input within the "Copy as cURL" feature. A remote attacker can trick the victim into copying a specially crafted URL, trick the victim into using this command and execute arbitrary commands on the system.

Mitigation

Install update from vendor's website.

Vulnerable software versions

Mozilla Thunderbird: 128.0 - 128.10.2

CPE2.3

External links

https://www.mozilla.org/en-US/security/advisories/mfsa2025-46/

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) Input validation error

EUVDB-ID: #VU109859

Risk: Medium

CVSSv4.0: 4.5 [CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2025-5265

CWE-ID: CWE-20 - Improper input validation

Exploit availability: No

Description

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

The vulnerability exists due to insufficient validation of user-supplied input within the "Copy as cURL" feature. A remote attacker can trick the victim into copying a specially crafted URL, trick the victim into using this command and execute arbitrary commands on the system.

The vulnerability affects Windows installations only.

Mitigation

Install update from vendor's website.

Vulnerable software versions

Mozilla Thunderbird: 128.0 - 128.10.2

CPE2.3

External links

https://www.mozilla.org/en-US/security/advisories/mfsa2025-46/

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.

5) Information disclosure

EUVDB-ID: #VU109875

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:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2025-5266

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 script elements loading cross-origin resources generated load and error events, which leaked information. A remote attacker can gain access to sensitive information.

Mitigation

Install update from vendor's website.

Vulnerable software versions

Mozilla Thunderbird: 128.0 - 128.10.2

CPE2.3

External links

https://www.mozilla.org/en-US/security/advisories/mfsa2025-46/

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.

6) Insufficient UI Warning of Dangerous Operations

EUVDB-ID: #VU109876

Risk: Low

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

CVE-ID: CVE-2025-5267

CWE-ID: CWE-357 - Insufficient UI Warning of Dangerous Operations

Exploit availability: No

Description

The vulnerability allows a remote attacker to perform clickjacking attacks.

The vulnerability exists due to an error in the UI that can lead to information disclosure. A remote attacker can perform a clickjacking attack and trick a user into leaking saved payment card details to a malicious page.

Mitigation

Install update from vendor's website.

Vulnerable software versions

Mozilla Thunderbird: 128.0 - 128.10.2

CPE2.3

External links

https://www.mozilla.org/en-US/security/advisories/mfsa2025-46/

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.

7) Buffer overflow

EUVDB-ID: #VU109877

Risk: High

CVSSv4.0: 6.1 [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]

CVE-ID: CVE-2025-5268

CWE-ID: CWE-119 - Memory corruption

Exploit availability: No

Description

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.

Mitigation

Install update from vendor's website.

Vulnerable software versions

Mozilla Thunderbird: 128.0 - 128.10.2

CPE2.3

External links

https://www.mozilla.org/en-US/security/advisories/mfsa2025-46/

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.

8) Buffer overflow

EUVDB-ID: #VU109878

Risk: High

CVSSv4.0: 6.1 [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]

CVE-ID: CVE-2025-5269

CWE-ID: CWE-119 - Memory corruption

Exploit availability: No

Description

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.

Mitigation

Install update from vendor's website.

Vulnerable software versions

Mozilla Thunderbird: 128.0 - 128.10.2

CPE2.3

External links

https://www.mozilla.org/en-US/security/advisories/mfsa2025-46/

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.

Risk	High
Patch available	YES
Number of vulnerabilities	8
CVE-ID	CVE-2025-5262 CVE-2025-5263 CVE-2025-5264 CVE-2025-5265 CVE-2025-5266 CVE-2025-5267 CVE-2025-5268 CVE-2025-5269
CWE-ID	CWE-415 CWE-388 CWE-20 CWE-200 CWE-357 CWE-119
Exploitation vector	Network
Public exploit	N/A
Vulnerable software	Mozilla Thunderbird Client/Desktop applications / Messaging software
Vendor	Mozilla