dbcve.org
FirefoxWeb browser · Mozilla

CVE-2023-4578

MEDIUM · 6.5 CVSS v3.1 Published 2023-09-11
Fix available
A fix is available. Upgrade to 115.2 / 117.0 or later.
See remediation →
72/100
Remediation priority · Elevated
Remotely reachable No privileges

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
When calling `JS::CheckRegExpSyntax` a Syntax Error could have been set which would end in calling `convertToRuntimeErrorAndClear`. A path in the function could attempt to allocate memory when none is available which would have caused a newly created Out of Memory exception to be mishandled as a Syntax Error. This vulnerability affects Firefox < 117, Firefox ESR < 115.2, and Thunderbird < 115.2.

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 vulnerability in the SpiderMonkey JavaScript engine's `JS::CheckRegExpSyntax` function causes Out of Memory (OOM) exceptions to be incorrectly mishandled as Syntax Errors. When memory allocation fails during a specific code path, the OOM exception is misclassified instead of being properly propagated, leading to incorrect error handling that could cause unexpected application behavior or crashes.

MitigationUpgrade to Firefox 117+, Firefox ESR 115.2+, or Thunderbird 115.2+ to receive the patch that corrects the OOM error handling in the RegExp syntax checking code path.

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:< 117.0
Firefox EsrWeb browser
Affected:< 115.2
ThunderbirdApplication
Affected:< 115.2

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
Required
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/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. Identify installed Mozilla product
    Check if Firefox, Firefox ESR, or Thunderbird is installed. On Windows, look in Program Files. On macOS, check /Applications. On Linux, check package manager or /usr/lib/firefox.
    Affected if Any of these three products is installed
  2. Check Firefox version
    Open Firefox, go to Help > About Firefox (or navigate to about:support). Note the version number displayed.
    Affected if Version is below 117.0 (e.g., 116.x, 115.x, etc.)
  3. Check Firefox ESR version
    Open Firefox ESR, go to Help > About Firefox ESR. Note the version number displayed.
    Affected if Version is below 115.2 (e.g., 115.1, 115.0, 102.x, etc.)
  4. Check Thunderbird version
    Open Thunderbird, go to Help > About Thunderbird. Note the version number displayed.
    Affected if Version is below 115.2 (e.g., 115.1, 115.0, etc.)

You are affected if you have Firefox below 117.0, Firefox ESR below 115.2, or Thunderbird below 115.2, as these versions contain the SpiderMonkey engine with the faulty OOM-to-SyntaxError mishandling in the JS::CheckRegExpSyntax function.

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 115.2 / 117.0 or later
Fixed in 115.2117.0
Interim mitigation

Upgrade to Firefox 117+, Firefox ESR 115.2+, or Thunderbird 115.2+ to receive the patch that corrects the OOM error handling in the RegExp syntax checking code path.

Recommended fix High confidence

Firefox 117.0, Firefox ESR 115.2, or Thunderbird 115.2 (or later)

  1. Check current installed version of Firefox, Firefox ESR, or Thunderbird
  2. Download the appropriate fixed version from the official Mozilla website (www.mozilla.org)
  3. For Firefox: Upgrade to version 117.0 or later
  4. For Firefox ESR: Upgrade to version 115.2 or later
  5. For Thunderbird: Upgrade to version 115.2 or later
  6. Restart the application after upgrade
  7. Verify the installed version matches the fixed release

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

Fix this in Firefox Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,080
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,328.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2023-4578 — 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-2023-4578 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