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CVE-2012-5840

31
FAUCET Score

CVE-2012-5840 is a critical use-after-free vulnerability in the nsTextEditorState::PrepareEditor function affecting Mozilla Firefox before 17.0, Thunderbird before 17.0, SeaMonkey before 2.14, and their respective ESR versions. This vulnerability carries a CVSS score of 9.3, indicating a high severity risk where remote attackers can exploit it with medium attack complexity to achieve arbitrary code execution or cause a denial of service through heap memory corruption. Despite its high severity, there is no evidence of active exploitation, publicly available exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 10.0.11CPE matchmatch criteria
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
< 17.0CPE matchmatch criteria
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
< 2.14CPE matchmatch criteria
cpe:2.3:a:mozilla:seamonkey:*:*:*:*:*:*:*:*
< 17.0CPE matchmatch criteria
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*
< 10.0.11CPE matchmatch criteria
cpe:2.3:a:mozilla:thunderbird_esr:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 2.0

9.3HIGH

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

Confidentiality Impact
COMPLETE
Integrity Impact
COMPLETE
Availability Impact
COMPLETE
Access Vector
NETWORK
Access Complexity
MEDIUM
Authentication
NONE
Exploitability Score
8.6
Impact Score
10.0
CvssVersion
2.0

Exploit Intelligence

EPSS Score
6.07%
Probability of exploitation in next 30 days
EPSS Percentile
92.6%
Percentile rank of EPSS score among Peer Group
As of 2026-07-26
Model: v2026.06.15
This CVE's current EPSS score of 0.0607 is in the 66th percentile among its peer group of 8,915 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

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)

mozillapatch availablevia nvd_reference
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 5Fixed in: firefox-0:10.0.11-1.el5_8
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 5Fixed in: xulrunner-0:10.0.11-1.el5_8
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 5Fixed in: thunderbird-0:10.0.11-1.el5_8
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 6Fixed in: firefox-0:10.0.11-1.el6_3
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 6Fixed in: xulrunner-0:10.0.11-1.el6_3
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 6Fixed in: thunderbird-0:10.0.11-1.el6_3
View patch

Vendor Advisories (1)

redhatCVE-2012-5840Critical

Mozilla: Use-after-free and buffer overflow issues found using Address Sanitizer (MFSA 2012-105)

Nov 20, 2012

References

lists.opensuse.org / opensuse-security-announce/2012-11/msg00021.html
Mailing ListThird Party Advisory
lists.opensuse.org / opensuse-security-announce/2013-01/msg00022.html
Mailing ListThird Party Advisory
lists.opensuse.org / opensuse-updates/2012-11/msg00090.html
Mailing ListThird Party Advisory
lists.opensuse.org / opensuse-updates/2012-11/msg00092.html
Mailing ListThird Party Advisory
lists.opensuse.org / opensuse-updates/2012-11/msg00093.html
Mailing ListThird Party Advisory
osvdb.org / 87606
Broken LinkThird Party Advisory
rhn.redhat.com / errata/RHSA-2012-1482.html
Third Party Advisory
rhn.redhat.com / errata/RHSA-2012-1483.html
Third Party Advisory
bugzilla.mozilla.org / show_bug.cgi
ExploitIssue TrackingPatchVendor Advisory
secunia.com / advisories/51359
Third Party Advisory
secunia.com / advisories/51360
Third Party Advisory
secunia.com / advisories/51369
Third Party Advisory
secunia.com / advisories/51370
Third Party Advisory
secunia.com / advisories/51381
Third Party Advisory
secunia.com / advisories/51434
Third Party Advisory
secunia.com / advisories/51439
Third Party Advisory
secunia.com / advisories/51440
Third Party Advisory
exchange.xforce.ibmcloud.com / vulnerabilities/80190
Third Party AdvisoryVDB Entry
oval.cisecurity.org / repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A16904
Third Party Advisory
mandriva.com / security/advisories
Third Party Advisory
mozilla.org / security/announce/2012/mfsa2012-105.html
Vendor Advisory
palemoon.org / releasenotes-ng.shtml
Broken Link
securityfocus.com / bid/56635
Third Party AdvisoryVDB Entry
ubuntu.com / usn/USN-1636-1
Third Party Advisory
ubuntu.com / usn/USN-1638-1
Third Party Advisory
ubuntu.com / usn/USN-1638-2
Third Party Advisory
ubuntu.com / usn/USN-1638-3
Third Party Advisory