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CVE-2015-2740

26
FAUCET Score

CVE-2015-2740 describes a critical buffer overflow vulnerability in the nsXMLHttpRequest::AppendToResponseText function affecting Mozilla Firefox, Firefox ESR, and Thunderbird. This flaw allows remote attackers to cause a denial of service and potentially achieve other unspecified impacts via unknown vectors. With a CVSS score of 10.0, it represents a severe risk, being easily exploitable over the network with no authentication required, and could lead to complete compromise of confidentiality, integrity, and availability. While no public exploit code or active exploitation is confirmed, the vulnerability garnered some community discussion and media coverage at the time of its disclosure.

Impacted Technologies

VendorProductVersion(s)CPE
<= 38.0.1CPE matchmatch criteria
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*
31.0CPE matchmatch criteria
cpe:2.3:a:mozilla:firefox:31.0:*:*:*:*:*:*:*
31.1.0CPE matchmatch criteria
cpe:2.3:a:mozilla:firefox:31.1.0:*:*:*:*:*:*:*
31.1.1CPE matchmatch criteria
cpe:2.3:a:mozilla:firefox:31.1.1:*:*:*:*:*:*:*
31.3.0CPE matchmatch criteria
cpe:2.3:a:mozilla:firefox:31.3.0:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 2.0

10.0HIGH

AV:N/AC:L/Au:N/C:C/I:C/A:C

Confidentiality Impact
COMPLETE
Integrity Impact
COMPLETE
Availability Impact
COMPLETE
Access Vector
NETWORK
Access Complexity
LOW
Authentication
NONE
Exploitability Score
10.0
Impact Score
10.0
CvssVersion
2.0

Exploit Intelligence

EPSS Score
5.55%
Probability of exploitation in next 30 days
EPSS Percentile
92.0%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0555 is in the 86th percentile among its peer group of 51,506 CVEs.

Social Chatter

No social media mentions found for this CVE.

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (7)

redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 6Fixed in: firefox-0:38.1.0-1.el6_6
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 5Fixed in: firefox-0:38.1.0-1.el5_11
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 5Fixed in: thunderbird-0:31.8.0-1.el5_11
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: thunderbird-0:31.8.0-1.ael7b_1
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 6Fixed in: thunderbird-0:31.8.0-1.el6_6
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: firefox-0:38.1.0-1.ael7b_1
View patch
mozillavendor investigatingvia nvd_reference
View patch

Vendor Advisories (1)

redhatCVE-2015-2740Critical

Mozilla: Vulnerabilities found through code inspection (MFSA 2015-66)

Jul 2, 2015

References

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