FirefoxWeb browser · Mozilla

CVE-2015-2733

HIGH · 10.0 CVSS v2.0 Published 2015-07-06

Fix available

A fix is available. Upgrade to after 38.1.0 or later.

See remediation →

100/100

Remediation priority · Urgent

Remotely reachable No privileges Zero-click

Official description

NVD · unedited

Use-after-free vulnerability in the CanonicalizeXPCOMParticipant function in Mozilla Firefox before 39.0 and Firefox ESR 31.x before 31.8 and 38.x before 38.1 allows remote attackers to execute arbitrary code via vectors involving attachment of an XMLHttpRequest object to a dedicated worker.

Technical summary

dbcve analysis · high confidence

Use-after-free vulnerability in Firefox's CanonicalizeXPCOMParticipant function allows remote code execution through malicious XMLHttpRequest objects attached to dedicated WebWorkers, causing memory corruption after object release.

MitigationUpgrade Firefox to version 39.0 or later (or ESR 31.8+/38.1+) across all affected endpoints; deploy via enterprise patch management tooling.

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

Affected products & versions

NVD · CPE data

FirefoxWeb browser

Affected:<= 38.1.0= 31.0= 31.1.0= 31.1.1= 31.3.0= 31.5.1= 31.5.2= 31.5.3= 38.0

Firefox EsrWeb browser

Affected:= 31.1= 31.2= 31.3= 31.4= 31.5= 31.6.0= 31.7.0

SolarisOperating system

Affected:= 11.3

Suse Linux Enterprise DesktopOperating system

Affected:= 11= 12.0

Suse Linux Enterprise ServerOperating system

Affected:= 12.0

CVSS breakdown

From the vector

Attack vector: Network
Complexity: Low
Authentication: None
Confidentiality: Complete
Integrity: Complete
Availability: Complete

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

Am I affected?

dbcve checks

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

Identify installed Firefox version

Run 'firefox --version' from command line, or check 'About Firefox' from the application menu, or query the system package manager (dpkg -l firefox, rpm -q firefox, pkginfo -l firefox)

Affected if Version matches any of: 38.1.0, 31.0, 31.1.0, 31.1.1, 31.3.0, 31.5.1, 31.5.2, 31.5.3, 38.0 (or falls within <= 38.1.0 range for unlisted 31.x/38.x versions)
Identify installed Firefox ESR version

Run 'firefox --version' and check the ESR designation, or query system packages (dpkg -l firefox-esr, rpm -q firefox-esr)

Affected if Version matches any of: 31.1, 31.2, 31.3, 31.4, 31.5, 31.6.0, 31.7.0 (or falls within the 31.x ESR range before 31.8.0)
Check for Firefox on Oracle Solaris 11.3

Query the Solaris package database: 'pkginfo -l firefox' or 'pkg list firefox'

Affected if Firefox package is installed on Solaris 11.3 (any version present indicates the vulnerable bundled browser)
Check for Firefox on SUSE Linux Enterprise

Query SUSE packages: 'rpm -q firefox' (SLED) or 'rpm -q firefox' (SLES)

Affected if Firefox package is installed on SUSE Linux Enterprise Desktop 11/12.0 or Server 12.0

A system is affected if any installed Firefox or Firefox ESR version matches the specific vulnerable versions listed (31.x through 31.7.0 or 38.0/38.1.0), or if Firefox is present on Solaris 11.3 or SUSE Linux Enterprise 11/12.0 systems.

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

Remediation

dbcve · scoped

Upgrade available Upgrade to a release after 38.1.0

Interim mitigation

Upgrade Firefox to version 39.0 or later (or ESR 31.8+/38.1+) across all affected endpoints; deploy via enterprise patch management tooling.

Recommended fix High confidence

Firefox 39.0 or later; Firefox ESR 31.8 or later; Firefox ESR 38.1 or later

Upgrade Firefox to version 39.0 or later
If using Firefox ESR 31.x, upgrade to Firefox ESR 31.8 or later
If using Firefox ESR 38.x, upgrade to Firefox ESR 38.1 or later
Restart the browser after upgrading

Caveat Review release notes for potential compatibility issues with existing add-ons or web applications

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

Fix this in Firefox Scoped from the published advisory

Consultation3.0 h
Implementation6.0 h
Testing3.0 h
Review / QA2.0 h

14.0 hours of engineering $2,490

Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,984.

Scan for this in your stack

Free · runs locally

dbcve dependency scanner

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References

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2015-2733 in production — separate from our analysis above.

Notes0 Guidelines

Know something about CVE-2015-2733?

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

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

At a glance

A fix existsUpgrade to after 38.1.0 or later

Severity 10.0 High

Exploit likelihood EPSS, next 30 days 6.2%

Affects: Firefox

Remediation

A high-priority fix

Fix this in Firefox 14 hrs · Moderate

Typical engagement from $2,490

Get a fix See the full breakdown ↓

A high-priority vulnerability. Send your environment and a specialist will scope CVE-2015-2733 and return a fixed quote and timeline.

You’ll deal with our team directly and deploy the reviewed fix to staging first — never straight to production.

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.

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.

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.

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.

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.

Check your environment

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.

Scan for this in your stack

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

Practitioner notes

No notes yet

Official description

Technical summary

Affected products & versions

CVSS breakdown

Am I affected?

Remediation

References