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FirefoxWeb browser · Mozilla

CVE-2016-1978

HIGH · 7.3 CVSS v3.0 Published 2016-03-13
Fix available
A fix is available. Upgrade to after 43.0.4 or later.
See remediation →
82/100
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
Use-after-free vulnerability in the ssl3_HandleECDHServerKeyExchange function in Mozilla Network Security Services (NSS) before 3.21, as used in Mozilla Firefox before 44.0, allows remote attackers to cause a denial of service or possibly have unspecified other impact by making an SSL (1) DHE or (2) ECDHE handshake at a time of high memory consumption.

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

Use-after-free vulnerability in NSS library's ssl3_HandleECDHServerKeyExchange function allows remote attackers to cause denial of service or possibly execute arbitrary code via specially crafted DHE or ECDHE SSL handshakes during high memory consumption scenarios.

MitigationUpgrade NSS library to version 3.21 or later, and Mozilla Firefox to 44.0 or later, to obtain the patched memory management code that fixes the use-after-free condition in ECDH server key exchange handling.

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:<= 43.0.4
Network Security ServicesApplication
Affected:<= 3.20.1

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
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
Low

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

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. Check installed Firefox version
    Open Firefox and navigate to Help > About Firefox, or run 'firefox --version' from command line
    Affected if Version displayed is 43.0.4 or earlier
  2. Check NSS library version
    Run 'nss-config --version' or check via system package manager (dpkg -l libnss3 on Debian/Ubuntu, rpm -q libnss3 on RHEL/CentOS)
    Affected if Version is 3.20.1 or earlier
  3. Verify SSL/TLS usage with ECDHE or DHE
    Check if the application or browser establishes SSL/TLS connections using DHE or ECDHE key exchange. For servers, review SSL configuration files for supported cipher suites containing 'DHE' or 'ECDHE'
    Affected if DHE or ECDHE cipher suites are enabled and used in SSL/TLS handshakes

Environment is affected if Firefox version is 43.0.4 or earlier, or NSS library version is 3.20.1 or earlier, and SSL/TLS connections using DHE or ECDHE key exchange are in 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 43.0.4
Interim mitigation

Upgrade NSS library to version 3.21 or later, and Mozilla Firefox to 44.0 or later, to obtain the patched memory management code that fixes the use-after-free condition in ECDH server key exchange handling.

Fix this in Firefox Scoped from the published advisory
  • Consultation8.0 h
  • Implementation16.0 h
  • Testing12.0 h
  • Review / QA8.0 h
44.0 hours of engineering $7,720
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $12,352.

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-2016-1978 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