Ubuntu LinuxOperating system · Canonical
CVE-2015-4478
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 · uneditedMozilla Firefox before 40.0 and Firefox ESR 38.x before 38.2 do not impose certain ECMAScript 6 requirements on JavaScript object properties, which allows remote attackers to bypass the Same Origin Policy via the reviver parameter to the JSON.parse method.
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 confidenceFirefox before 40.0 and Firefox ESR 38.x before 38.2 failed to enforce certain ECMAScript 6 requirements on JavaScript object properties when using the reviver parameter in JSON.parse. This allowed malicious pages to bypass the Same Origin Policy by manipulating how the reviver function handles property enumeration, potentially accessing sensitive data from other origins.
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
Ubuntu LinuxOperating system
= 12.04= 14.04= 15.04
FirefoxWeb browser
<= 39.0.3= 38.0= 38.0.1= 38.0.5= 38.1.0= 13.1= 13.2CVSS 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
- Partial
- Availability
- None
AV:N/AC:L/Au:N/C:N/I:P/A:N
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 checksWork through these to decide whether this CVE applies to you.
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Identify Firefox versionOpen Firefox, click Menu > Help > About Firefox, or run 'firefox --version' from command lineAffected if Version is 38.0, 38.0.1, 38.0.5, 38.1.0, or any version <= 39.0.3 (including 39.x lines below 40.0)
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Confirm ESR version statusCheck the version string for ESR designation or check installed package info (e.g., dpkg -l firefox-esr or rpm -qi firefox-esr)Affected if ESR version is 38.0, 38.0.1, 38.0.5, or 38.1.0 (any version before 38.2)
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Verify browser is used for web accessDetermine if Firefox is actively used to browse web pages, since exploitation requires visiting a malicious webpage that uses JSON.parse with a reviver functionAffected if Browser is used to visit or render untrusted web content
If Firefox version is <= 39.0.3 or ESR 38.x <= 38.1.0, and the browser is used to access web content, the environment is vulnerable to Same Origin Policy bypass via JSON.parse reviver manipulation.
Generated from the published advisory. Verify against your own configuration.
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 dataUpgrade Firefox to version 40.0 or later (or Firefox ESR 38.2 or later) to obtain the patched browser that properly enforces ECMAScript 6 property requirements in JSON.parse reviver functions.
Fix this in Ubuntu Linux
Scoped from the published advisory
- Consultation1.0 h
- Implementation2.0 h
- Testing1.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,424.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2015-4478 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sources- www.mozilla.org
- lists.opensuse.org
- lists.opensuse.org
- lists.opensuse.org
- lists.opensuse.org
- lists.opensuse.org
- lists.opensuse.org
- lists.opensuse.org
- rhn.redhat.com
- www.debian.org
- www.oracle.com
- www.securitytracker.com
- www.ubuntu.com
- www.ubuntu.com
- www.ubuntu.com
- bugzilla.mozilla.org
- security.gentoo.org
- nvd.nist.gov
Practitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2015-4478 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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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.
- 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