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FirefoxWeb browser · Mozilla

CVE-2017-5373

CRITICAL · 9.8 CVSS v3.0 Published 2018-06-11
Fix available
A fix is available. Upgrade to 45.7.0 / 51.0 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
Memory safety bugs were reported in Firefox 50.1 and Firefox ESR 45.6. Some of these bugs showed evidence of memory corruption and we presume that with enough effort that some of these could be exploited to run arbitrary code. This vulnerability affects Thunderbird < 45.7, Firefox ESR < 45.7, and Firefox < 51.

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 · moderate confidence

Memory safety bugs in Firefox and Thunderbird allow memory corruption that can potentially be exploited for arbitrary code execution. The vulnerability stems from unspecified memory handling issues in the affected versions.

MitigationUpgrade to Firefox 51 or later, Firefox ESR 45.7 or later, or Thunderbird 45.7 or later to patch the memory corruption vulnerabilities.

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:< 45.7.0< 51.0
Debian LinuxOperating system
Affected:= 8.0
Enterprise Linux DesktopOperating system
Affected:= 5.0= 6.0= 7.0
Enterprise Linux ServerOperating system
Affected:= 5.0= 6.0= 7.0
Enterprise Linux WorkstationOperating system
Affected:= 5.0= 6.0= 7.0
ThunderbirdApplication
Affected:< 45.7.0

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
High
Integrity
High
Availability
High

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

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
    Run 'firefox --version' or 'rpm -qa firefox' on Linux, or check Help > About Firefox in the application menu on any OS
    Affected if Version is below 51.0 (any Firefox prior to 51.0 is affected; versions 45.7.0 through 50.x require the specific 45.7 ESR patch)
  2. Check installed Thunderbird version
    Run 'thunderbird --version' or 'rpm -qa thunderbird' on Linux, or check Help > About Thunderbird in the application menu
    Affected if Version is below 45.7.0
  3. Verify Firefox ESR version if applicable
    Run 'firefox --version' and confirm if it is an ESR (Extended Support Release) build; ESR versions display 'ESR' in the version string
    Affected if ESR version is below 45.7
  4. Check Red Hat browser package versions (if using RHEL bundled Firefox)
    Run 'rpm -q firefox' to list the installed Firefox package version from Red Hat repositories
    Affected if The packaged Firefox version corresponds to an unpatched release below 51.0
  5. Check Debian browser package versions (if using Debian bundled Firefox)
    Run 'dpkg -l firefox' or check apt policy firefox to see the installed version from Debian repositories
    Affected if The Debian-packaged Firefox version is below the patched version provided for Debian 8.0

If Firefox version is below 51.0 or Thunderbird version is below 45.7.0, the environment is affected by this memory corruption vulnerability.

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 45.7.0 / 51.0 or later
Fixed in 45.7.051.0
Interim mitigation

Upgrade to Firefox 51 or later, Firefox ESR 45.7 or later, or Thunderbird 45.7 or later to patch the memory corruption vulnerabilities.

Recommended fix High confidence

Firefox 51+ (or Firefox ESR 45.7+); Thunderbird 45.7+

  1. For Firefox users: Upgrade to Firefox 51 or later. If using ESR, upgrade to Firefox ESR 45.7 or later.
  2. For Thunderbird users: Upgrade to Thunderbird 45.7 or later.
  3. On Debian Linux 8.0: Run 'apt-get update && apt-get upgrade' to apply security updates for Firefox and Thunderbird.
  4. On Enterprise Linux (RHEL/CentOS 5/6/7): Run 'yum update firefox' or 'yum update thunderbird' to install the patched versions.
  5. Verify the installed version by checking Help > About Firefox or running 'firefox --version' in the terminal.
Caveat Newer Firefox versions may not be compatible with very old extensions or plugins; test critical workflows after upgrade

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

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
Get the upgrade done

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

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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-2017-5373 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