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FirefoxWeb browser · Mozilla

CVE-2011-2377

MEDIUM · 5.0 CVSS v2.0 Published 2011-06-30
Fix available
A fix is available. Upgrade to after 3.6.17 or later.
See remediation →
59/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click

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 3.6.18 and 4.x through 4.0.1, Thunderbird before 3.1.11, and SeaMonkey through 2.0.14 allow remote attackers to cause a denial of service (memory corruption and application crash) or possibly execute arbitrary code via a multipart/x-mixed-replace image.

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 · high confidence

Memory corruption vulnerability in how Mozilla Firefox, Thunderbird, and SeaMonkey parse multipart/x-mixed-replace images. This content type allows servers to continuously push replacement images, and improper handling can lead to memory corruption enabling denial of service or potentially arbitrary code execution.

MitigationUpgrade affected Mozilla products to patched versions: Firefox 3.6.18/4.0.2+, Thunderbird 3.1.11+, or SeaMonkey 2.0.15+. Apply via standard software patch management processes.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

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:<= 3.6.17= 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= 1.5= 1.5.0.1
SeamonkeyApplication
Affected:= 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= 1.1.1
ThunderbirdApplication
Affected:<= 3.1.10= 0.1= 0.2= 0.3= 0.4= 0.5= 0.6= 0.7= 0.7.1= 0.7.2= 0.7.3= 0.8

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
Low
Authentication
None
Confidentiality
None
Integrity
None
Availability
Partial

AV:N/AC:L/Au:N/C:N/I:N/A:P

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed Mozilla product
    Check which Mozilla application is installed: look for Firefox, Thunderbird, or SeaMonkey in installed programs or by launching the application and checking Help > About
    Affected if Any of Firefox, Thunderbird, or SeaMonkey is installed
  2. Determine Firefox version
    In Firefox, go to Help > About Firefox. The version number is displayed next to the application name
    Affected if Firefox version is 1.0 through 1.0.8, 1.5.0 through 1.5.0.1, or 3.6.17 or earlier
  3. Determine SeaMonkey version
    In SeaMonkey, go to Help > About SeaMonkey. The version number is displayed
    Affected if SeaMonkey version is 1.0 through 1.0.9, 1.1, or 1.1.1
  4. Determine Thunderbird version
    In Thunderbird, go to Help > About Thunderbird. The version number is displayed
    Affected if Thunderbird version is 0.1 through 0.8, or 3.1.10 or earlier
  5. Assess exposure to multipart/x-mixed-replace content
    This vulnerability is triggered when the application parses multipart/x-mixed-replace images, which are used in some web streams and webcams. The affected condition exists if an affected version is used to browse the web or view email with remote images
    Affected if An affected version is in use for web browsing or email viewing where multipart/x-mixed-replace image streams could be encountered

A user is affected if they have Firefox 1.0-1.0.8, 1.5.x, or 3.6.17 and earlier; SeaMonkey 1.0-1.1.1; or Thunderbird 0.x or 3.1.10 and earlier, and they browse web content or view email that could contain multipart/x-mixed-replace images.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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.

From vendor data
Upgrade available Upgrade to a release after 3.6.17
Interim mitigation

Upgrade affected Mozilla products to patched versions: Firefox 3.6.18/4.0.2+, Thunderbird 3.1.11+, or SeaMonkey 2.0.15+. Apply via standard software patch management processes.

Fix this in Firefox Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing1.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,090
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,744.

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-2011-2377 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