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Weekly Signal
Live intelligence Updated 20 Aug 2026 · 12:21 UTC

Mozilla · Firefox, Multiple Products, Seamonkey +1 more

CVE-2010-3765

Mozilla Multiple Products Remote Code Execution Vulnerability

Recommended action

Validate affected assets and exposure now, then remediate on an accelerated schedule. Debian Security advisory Dsa 2124

View response plan
CVSS9.8
EPSS83.3%
KEVYes
ExploitationConfirmed exploitation
RemediationNot yet verified ↓

Assessment

Why it matters

CISA lists this vulnerability as known to be exploited; exploitation is confirmed; EPSS is 83.3%; technical severity is CVSS 9.8.

Mozilla Firefox 3.5.x through 3.5.14 and 3.6.x through 3.6.11, Thunderbird 3.1.6 before 3.1.6 and 3.0.x before 3.0.10, and SeaMonkey 2.x before 2.0.10, when JavaScript is enabled, allows remote attackers to execute arbitrary code via vectors related to nsCSSFrameConstructor::ContentAppended, the appendChild method, incorrect index tracking, and the creation of multiple frames, which triggers memory corruption, as exploited in the wild in October 2010 by the Belmoo malware.

Who should care

  • Teams operating Firefox, Multiple Products, Seamonkey +1 more
  • Vulnerability and exposure management teams
  • Security operations teams monitoring exploitation activity

Response plan

What I would do

  1. Confirm whether Firefox, Multiple Products, Seamonkey +1 more is present in the environment.
  2. Identify affected versions and establish whether vulnerable services are exposed or reachable.
  3. Debian Security advisory Dsa 2124
  4. Review relevant security telemetry for evidence of attempted or successful exploitation.
  5. Document the remediation decision and track it to verified completion.

Treatment intelligence

Remediation intelligence

Not yet verified

Vendor sources are listed before government and third-party guidance. Confirm product applicability and change prerequisites before deployment.

Verification noteAutomated link verification has not completed for this guidance yet.

Advisory

Required Action

Technical details

CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CWE
CWE-119
Affected versions
Mozilla Firefox (Version 3.5 | Version 3.5.1 | Version 3.5.2 | Version 3.5.3); Mozilla Multiple Products; Mozilla Seamonkey (Version 2.0 | Version 2.0 | Version 2.0 | Version 2.0); Mozilla Thunderbird (Version 3.0.1 | Version 3.0.2 | Version 3.0.3 | Version 3.0.4)
Fixed versions
No explicit fixed version is currently recorded.
Published
27 October 2010
Attack vector
Network
Privileges required
None
User interaction
None

Signal timeline

  1. CVE published
  2. Added to CISA KEV
  3. Latest EPSS score: 83.3%
  4. Signal calculated at 83

External references

Live public intelligence This assessment combines public-source evidence. Validate the affected product, version and exposure against your own environment before making a risk decision.