CVE-2012-5840

Severity: critical (CVSS 9.3 v2.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 6.1% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2012-11-21 · updated 2026-06-16
Weakness: CWE-416

Description

Use-after-free vulnerability in the nsTextEditorState::PrepareEditor function in Mozilla Firefox before 17.0, Firefox ESR 10.x before 10.0.11, Thunderbird before 17.0, Thunderbird ESR 10.x before 10.0.11, and SeaMonkey before 2.14 allows remote attackers to execute arbitrary code or cause a denial of service (heap memory corruption) via unspecified vectors, a different vulnerability than CVE-2012-4214.

Affected products

Canonical Ubuntu Linux: 10.04, 11.10, 12.04, 12.10
Mozilla Firefox: before 10.0.11; before 17.0 — fixed in 10.0.11, 17.0
Mozilla Seamonkey: before 2.14 — fixed in 2.14
Mozilla Thunderbird: before 17.0 — fixed in 17.0
Mozilla Thunderbird ESR: before 10.0.11 — fixed in 10.0.11
Opensuse: 11.4, 12.1, 12.2
RedHat Enterprise Linux Desktop: 5.0, 6.0
RedHat Enterprise Linux Eus: 6.3
RedHat Enterprise Linux Server: 5.0, 6.0
RedHat Enterprise Linux Workstation: 5.0, 6.0
SUSE Linux Enterprise Server 15 SP1: 10-sp4, 11-sp2
SUSE Linux Enterprise Server: 10-sp4, 11-sp2
SUSE Linux Enterprise Software Development Kit: 10-sp4, 11-sp2

How to fix

Upgrade to a fixed version: Mozilla Firefox 10.0.11, 17.0; Mozilla Seamonkey 2.14; Mozilla Thunderbird 17.0; Mozilla Thunderbird ESR 10.0.11. Check the vendor advisory for mitigations.

References

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