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FirefoxWeb browser · Mozilla

CVE-2009-3376

HIGH · 9.3 CVSS v2.0 Published 2009-10-29
Fix available
A fix is available. Upgrade to after 1.5.0.10 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Mozilla Firefox before 3.0.15 and 3.5.x before 3.5.4, and SeaMonkey before 2.0, does not properly handle a right-to-left override (aka RLO or U+202E) Unicode character in a download filename, which allows remote attackers to spoof file extensions via a crafted filename, as demonstrated by displaying a non-executable extension for an executable file.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis

A detailed technical summary for this CVE is being prepared.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
FirefoxWeb browser
Affected:= 3.0= 3.0.1= 3.0.2= 3.0.3= 3.0.4= 3.0.5= 3.0.6= 3.0.7= 3.0.8= 3.0.9= 3.0.10= 3.0.11
SeamonkeyApplication
Affected:<= 1.5.0.10= 1.0= 1.0.1= 1.0.2= 1.0.3= 1.0.4= 1.0.5= 1.0.6= 1.0.7= 1.0.8= 1.0.9= 1.1

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
M
Authentication
None
Confidentiality
Complete
Integrity
Complete
Availability
Complete

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

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to a release after 1.5.0.10
Vendor patch www.mozilla.org →
Recommended fix High confidence

Firefox 3.0.15 or 3.5.4+, SeaMonkey 2.0

  1. Check current Firefox or SeaMonkey version by navigating to Help > About or using 'firefox -version'/'seamonkey -version' command
  2. Back up important bookmarks, passwords, and settings using the Firefox/SeaMonkey backup feature or by copying the profile folder
  3. Upgrade Firefox to version 3.0.15 or 3.5.4 (or higher in the 3.5.x branch) by downloading from the official Mozilla website https://www.mozilla.org/
  4. If using SeaMonkey, upgrade to version 2.0 or higher from the SeaMonkey website
  5. After installation, restore bookmarks and settings from the backup
  6. Verify the new version is installed by checking Help > About
Caveat Minor: Some older extensions or plugins may not be compatible with Firefox 3.5.x; verify extension compatibility before upgrading

Generated from the published advisory — verify against the referenced sources before acting.

We can identify the exact fixed release, upgrade, and verify it in staging — typical engagement from $1,950. Get the upgrade done

Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2009-3376 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data