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CVE-2012-5839

31
FAUCET Score

CVE-2012-5839 describes a heap-based buffer overflow in the gfxShapedWord::CompressedGlyph::IsClusterStart function affecting Mozilla Firefox, Thunderbird, and SeaMonkey. This vulnerability carries a critical CVSS score of 9.3, indicating it can be exploited remotely with medium attack complexity to achieve complete compromise of confidentiality, integrity, and availability. Despite its high severity and potential for arbitrary code execution, there is no known active exploitation, public 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
7.00%
Probability of exploitation in next 30 days
EPSS Percentile
93.5%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0700 is in the 70th percentile among its peer group of 8,918 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.1 Bluesky, 0.1 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-2012-5839Critical

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 / 87607
Broken Link
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
Issue 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/80196
Third Party AdvisoryVDB Entry
oval.cisecurity.org / repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A16968
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/56637
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