CVE-2015-2740

CVE-2015-2740 is a critical-severity vulnerability in Mozilla Thunderbird with a CVSS 2.0 base score of 10.0. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-119.

Key facts

• Severity: Critical (CVSS 2.0 base score 10.0)
• EPSS exploit prediction: 6% (92nd percentile)
• Actively exploited: Not listed in CISA KEV
• Weakness: CWE-119
• Affected product: Mozilla Thunderbird
• Published: 2015-07-06
• Last modified: 2026-06-17

Description

Buffer overflow in the nsXMLHttpRequest::AppendToResponseText function in Mozilla Firefox before 39.0, Firefox ESR 31.x before 31.8 and 38.x before 38.1, and Thunderbird before 38.1 might allow remote attackers to cause a denial of service or have unspecified other impact via unknown vectors.

Frequently asked questions

What is CVE-2015-2740?

Buffer overflow in the nsXMLHttpRequest::AppendToResponseText function in Mozilla Firefox before 39.0, Firefox ESR 31.x before 31.8 and 38.x before 38.1, and Thunderbird before 38.1 might allow remote attackers to cause a denial of service or have unspecified other impact via unknown vectors.

How severe is CVE-2015-2740?

CVE-2015-2740 has a CVSS 2.0 base score of 10.0, rated critical severity.

Is CVE-2015-2740 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 6% (92nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2015-2740?

CVE-2015-2740 primarily affects Mozilla Thunderbird. In total, 28 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2015-2740?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2015-2740 published?

CVE-2015-2740 was published on 2015-07-06 and last updated on 2026-06-17.

References

• http://lists.opensuse.org/opensuse-security-announce/2015-07/msg00025.html
• http://lists.opensuse.org/opensuse-security-announce/2015-07/msg00031.html
• http://lists.opensuse.org/opensuse-security-announce/2015-07/msg00033.html
• http://lists.opensuse.org/opensuse-security-announce/2015-07/msg00034.html
• http://lists.opensuse.org/opensuse-security-announce/2015-08/msg00021.html
• http://rhn.redhat.com/errata/RHSA-2015-1207.html
• http://rhn.redhat.com/errata/RHSA-2015-1455.html
• http://www.debian.org/security/2015/dsa-3300
• http://www.debian.org/security/2015/dsa-3324
• http://www.mozilla.org/security/announce/2015/mfsa2015-66.html
• http://www.oracle.com/technetwork/topics/security/bulletinapr2016-2952098.html
• http://www.oracle.com/technetwork/topics/security/bulletinoct2015-2511968.html
• http://www.securityfocus.com/bid/75541
• http://www.securitytracker.com/id/1032783
• http://www.securitytracker.com/id/1032784
• http://www.ubuntu.com/usn/USN-2656-1
• http://www.ubuntu.com/usn/USN-2656-2
• http://www.ubuntu.com/usn/USN-2673-1
• https://bugzilla.mozilla.org/show_bug.cgi?id=1170809
• https://security.gentoo.org/glsa/201512-10

Affected products (28)

• cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:31.0:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:31.1.0:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:31.1.1:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:31.3.0:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:31.5.1:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:31.5.2:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:31.5.3:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:38.0:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox_esr:31.1:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox_esr:31.2:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox_esr:31.3:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox_esr:31.4:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox_esr:31.5:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox_esr:31.6.0:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox_esr:31.7.0:*:*:*:*:*:*:*
• cpe:2.3:a:novell:suse_linux_enterprise_software_development_kit:12.0:*:*:*:*:*:*:*
• cpe:2.3:o:canonical:ubuntu_linux:12.04:*:*:*:lts:*:*:*
• cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:lts:*:*:*
• cpe:2.3:o:canonical:ubuntu_linux:14.10:*:*:*:*:*:*:*
• cpe:2.3:o:canonical:ubuntu_linux:15.04:*:*:*:*:*:*:*
• cpe:2.3:o:debian:debian_linux:7.0:*:*:*:*:*:*:*
• cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*
• cpe:2.3:o:novell:suse_linux_enterprise_desktop:12.0:*:*:*:*:*:*:*
• cpe:2.3:o:novell:suse_linux_enterprise_server:11:sp4:*:*:*:*:*:*
• cpe:2.3:o:novell:suse_linux_enterprise_server:12.0:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
• cpe:2.3:o:oracle:solaris:11.3:*:*:*:*:*:*:*

More vulnerabilities in Mozilla Thunderbird

• CVE-2026-4692 — Critical (CVSS 10.0): Sandbox escape in the Responsive Design Mode component. This vulnerability was fixed in Firefox 149, Firefox ESR…
• CVE-2026-4689 — Critical (CVSS 10.0): Sandbox escape due to incorrect boundary conditions, integer overflow in the XPCOM component. This vulnerability was…
• CVE-2026-2778 — Critical (CVSS 10.0): Sandbox escape due to incorrect boundary conditions in the DOM: Core & HTML component. This vulnerability was fixed in…
• CVE-2026-2776 — Critical (CVSS 10.0): Sandbox escape due to incorrect boundary conditions in the Telemetry component in External Software. This vulnerability…
• CVE-2026-2768 — Critical (CVSS 10.0): Sandbox escape in the Storage: IndexedDB component. This vulnerability was fixed in Firefox 148, Firefox ESR 140.8,…
• CVE-2026-2761 — Critical (CVSS 10.0): Sandbox escape in the Graphics: WebRender component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33,…

All CVEs affecting Mozilla Thunderbird →

Other CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer) vulnerabilities

• CVE-2026-2778 — Critical (CVSS 10.0): Sandbox escape due to incorrect boundary conditions in the DOM: Core & HTML component. This vulnerability was fixed in…
• CVE-2026-2776 — Critical (CVSS 10.0): Sandbox escape due to incorrect boundary conditions in the Telemetry component in External Software. This vulnerability…
• CVE-2025-1866 — Critical (CVSS 10.0): Improper Restriction of Operations within the Bounds of a Memory Buffer vulnerability in warmcat libwebsockets allows…
• CVE-2022-27625 — Critical (CVSS 10.0): A vulnerability regarding improper restriction of operations within the bounds of a memory buffer is found in the…
• CVE-2022-27624 — Critical (CVSS 10.0): A vulnerability regarding improper restriction of operations within the bounds of a memory buffer is found in the…
• CVE-2020-11896 — Critical (CVSS 10.0): The Treck TCP/IP stack before 6.0.1.66 allows Remote Code Execution, related to IPv4 tunneling.

Browse all CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer) vulnerabilities →