dbcve.org
FirefoxWeb browser · Mozilla

CVE-2009-4102

HIGH · 9.3 CVSS v2.0 Published 2009-11-29
Fix available
A fix is available. Upgrade to after 1.4.3 or later.
See remediation →
100/100
Remediation priority · Urgent
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
Sage 1.4.3 and earlier extension for Firefox performs certain operations with chrome privileges, which allows remote attackers to execute arbitrary commands and perform cross-domain scripting attacks via the description tag of an RSS feed.

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

The Sage Firefox extension versions 1.4.3 and earlier processes RSS feed content with elevated chrome privileges, allowing remote attackers to inject arbitrary commands and perform cross-domain scripting by embedding malicious payloads in the description tag of an RSS feed.

MitigationRemove or disable the vulnerable Sage extension until an updated version is available; avoid subscribing to untrusted RSS feeds during the interim.

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:all versions
SageApplication
Affected:<= 1.4.3= 1.3.8

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
M
Authentication
None
Confidentiality
Complete
Integrity
Complete
Availability
Complete

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

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. Verify Firefox is installed
    Check for Firefox installation directory (e.g., C:\Program Files\Mozilla Firefox on Windows or /Applications/Firefox.app on macOS) or run: firefox --version (Linux) or check Add/Remove Programs (Windows)
    Affected if Firefox is present on the system - this is a prerequisite for the Sage extension to run
  2. Check if Sage extension is installed
    Navigate to Firefox Add-ons Manager (Tools > Add-ons) or inspect the extensions folder in the Firefox profile: %APPDATA%\Mozilla\Firefox\Profiles\*\extensions\ on Windows, ~/Library/Application Support/Firefox/Profiles/*/extensions/ on macOS, or ~/.mozilla/firefox/*/extensions/ on Linux. Look for sage.mozdev.org or a related extension file.
    Affected if The Sage extension is installed in Firefox
  3. Determine Sage extension version
    In Firefox Add-ons Manager, click on the Sage extension and view the version information displayed, or inspect the install.rdf or manifest.json file within the extension folder to read the version attribute.
    Affected if The installed version is readable and can be compared against affected ranges
  4. Compare version against affected ranges
    If version is found, compare it to: <= 1.4.3 or = 1.3.8. The extension manifest file (install.rdf) typically contains a line like <em:version>1.4.3</em:version> that shows the exact version.
    Affected if Version is 1.4.3 or earlier, or specifically 1.3.8

If Firefox is running with the Sage extension installed and its version is 1.4.3 or earlier (including 1.3.8), the environment is vulnerable to cross-domain scripting attacks via malicious RSS feed description tags.

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.

dbcve · scoped
Upgrade available Upgrade to a release after 1.4.3
Interim mitigation

Remove or disable the vulnerable Sage extension until an updated version is available; avoid subscribing to untrusted RSS feeds during the interim.

Recommended fix High confidence
  1. Uninstall the vulnerable Sage extension from Firefox immediately, as it is no longer maintained and contains a critical vulnerability allowing arbitrary command execution via malicious RSS feed description tags.
  2. Migrate to a maintained RSS feed reader extension or standalone application. Recommended alternatives include: Firefox's built-in RSS support (via Live Bookmarks), Feedly, or other actively developed feed readers.
  3. If continued use of Sage is absolutely required in legacy environments, disable JavaScript in Firefox and exercise extreme caution when previewing any RSS feeds from untrusted sources.
Caveat The Sage extension is abandoned and no longer maintained. There is no official fixed version. Users must migrate to alternative feed readers.

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

Fix this in Firefox Scoped from the published advisory
  • Consultation6.0 h
  • Implementation12.0 h
  • Testing6.0 h
  • Review / QA4.0 h
28.0 hours of engineering $4,980
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $7,968.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2009-4102 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

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-2009-4102 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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