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FirefoxWeb browser · Mozilla

CVE-2013-1720

MEDIUM · 6.8 CVSS v2.0 Published 2013-09-18
Fix available
A fix is available. Upgrade to after 23.0.1 or later.
See remediation →
77/100
Remediation priority · High
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
The nsHtml5TreeBuilder::resetTheInsertionMode function in the HTML5 Tree Builder in Mozilla Firefox before 24.0, Thunderbird before 24.0, and SeaMonkey before 2.21 does not properly maintain the state of the insertion-mode stack for template elements, which allows remote attackers to execute arbitrary code or cause a denial of service (heap-based buffer over-read) by triggering use of this stack in its empty state.

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

Heap-based buffer over-read vulnerability in Mozilla Firefox, Thunderbird, and SeaMonkey where the nsHtml5TreeBuilder::resetTheInsertionMode function fails to properly maintain the insertion-mode stack state for template elements, allowing the stack to be accessed in an empty state and potentially executing arbitrary code.

MitigationUpgrade to Firefox 24.0, Thunderbird 24.0, SeaMonkey 2.21 or later. For systems that cannot be immediately upgraded, consider disabling or restricting HTML5 parsing capabilities as a temporary workaround.

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:<= 23.0.1= 19.0= 19.0.1= 19.0.2= 20.0= 20.0.1= 21.0= 22.0= 23.0
ThunderbirdApplication
Affected:<= 17.0.9= 17.0= 17.0.1= 17.0.2= 17.0.3= 17.0.4= 17.0.5= 17.0.6= 17.0.7= 17.0.8
SeamonkeyApplication
Affected:<= 2.20= 2.0= 2.0.1= 2.0.2= 2.0.3= 2.0.4= 2.0.5= 2.0.6= 2.0.7= 2.0.8= 2.0.9= 2.0.10

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
Partial
Integrity
Partial
Availability
Partial

AV:N/AC:M/Au:N/C:P/I:P/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. On Windows, look in Program Files for 'Mozilla Firefox', 'Mozilla Thunderbird', or 'SeaMonkey'. On Linux, check /usr/bin for firefox, thunderbird, or seamonkey. On macOS, check /Applications.
    Affected if Any of Firefox, Thunderbird, or SeaMonkey is installed
  2. Determine product version
    For Firefox: run 'firefox --version' or open Firefox and go to Help > About. For Thunderbird: run 'thunderbird --version' or open Thunderbird and go to Help > About. For SeaMonkey: run 'seamonkey --version' or open SeaMonkey and go to Help > About.
    Affected if The displayed version matches any version in the affected list (Firefox <= 23.0.1 or versions 19.0-23.0; Thunderbird <= 17.0.9 or versions 17.0-17.0.8; SeaMonkey <= 2.20 or versions 2.0-2.0.10)
  3. Verify HTML5 parsing is in use
    The vulnerability exists in nsHtml5TreeBuilder, the HTML5 parser component. This parser is used when parsing HTML5 documents. No specific configuration disablement is required for detection - the vulnerable code path is exercised during normal HTML document parsing.
    Affected if HTML content is being processed by the application (this is the default behavior for all three products)

You are affected if any of Firefox (versions 19.0 through 23.0.1), Thunderbird (versions 17.0 through 17.0.9), or SeaMonkey (versions 2.0 through 2.20) is installed and HTML content is processed, which occurs during normal application use.

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 23.0.1
Interim mitigation

Upgrade to Firefox 24.0, Thunderbird 24.0, SeaMonkey 2.21 or later. For systems that cannot be immediately upgraded, consider disabling or restricting HTML5 parsing capabilities as a temporary workaround.

Fix this in Firefox Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing1.0 h
  • Review / QA1.0 h
5.0 hours of engineering $890
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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-2013-1720 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