dbcve.org
FirefoxWeb browser · Mozilla

CVE-2026-8388

MEDIUM · 6.5 CVSS v3.1 Published 2026-05-12
Fix available
A fix is available. Upgrade to 150.0.3 or later.
See remediation →
74/100
Remediation priority · Elevated
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
Incorrect boundary conditions in the JavaScript Engine: JIT component. This vulnerability was fixed in Firefox 150.0.3, Firefox ESR 115.36, Firefox ESR 140.11, and Thunderbird 140.11.

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 boundary condition vulnerability in the JavaScript Engine's JIT (Just-In-Time) compiler allows improper memory access due to insufficient boundary checks. This could potentially be exploited for memory corruption, possibly leading to arbitrary code execution or information disclosure.

MitigationUpdate affected installations to Firefox 150.0.3, Firefox ESR 115.36, Firefox ESR 140.11, or Thunderbird 140.11 to remediate the vulnerability.

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:< 150.0.3

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
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

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. Verify Firefox is installed
    Check for Firefox installation by looking in standard installation directories or using package management tools (e.g., dpkg -l | grep firefox on Debian-based systems, or Get-ItemProperty on Windows in HKLM:\SOFTWARE\Mozilla\Mozilla Firefox)
    Affected if Firefox is not found on the system, then the system is not vulnerable to this specific CVE which targets Firefox
  2. Determine installed Firefox version
    Access the Firefox About page (Help > About Firefox) or run the command: firefox --version on Linux, or query the Windows registry key HKLM:\SOFTWARE\Mozilla\Mozilla Firefox\CurrentVersion
    Affected if Unable to determine the installed version prevents assessment of vulnerability status
  3. Compare version against affected range
    Compare the obtained version number to the affected range: any version of Mozilla Firefox prior to 150.0.3 is considered affected (e.g., 150.0.2, 149.x, 148.x, etc.)
    Affected if The installed version is lower than 150.0.3 (for example, 150.0.2, 149.0.1, or any 148.x release)
  4. Confirm JIT compiler is enabled
    The JavaScript JIT compiler is enabled by default in Firefox. Verify by navigating to about:config in the Firefox address bar and checking that the option javascript.options.jit.content is set to true (default)
    Affected if The JIT compiler is explicitly disabled (javascript.options.jit.content set to false), the exploitation surface for this specific vulnerability is reduced, though other memory corruption vectors may still exist

If Firefox is installed with a version below 150.0.3 and the JavaScript JIT compiler remains enabled (default), the environment is vulnerable to CVE-2026-8388.

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 150.0.3 or later
Fixed in 150.0.3
Interim mitigation

Update affected installations to Firefox 150.0.3, Firefox ESR 115.36, Firefox ESR 140.11, or Thunderbird 140.11 to remediate the vulnerability.

Recommended fix High confidence

Firefox 150.0.3 or later (or Firefox ESR 115.36/140.11 for ESR deployments)

  1. 1. Check current Firefox version: Click Help > About Firefox
  2. 2. Navigate to https://www.mozilla.org/en-US/firefox/download/ and download Firefox 150.0.3 or later
  3. 3. Close all running Firefox instances
  4. 4. Install the downloaded Firefox version
  5. 5. After installation, verify the fix by checking Help > About Firefox shows version 150.0.3 or higher
  6. 6. For enterprise environments using ESR, upgrade to Firefox ESR 115.36, Firefox ESR 140.11, or later per the support lifecycle

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
  • Testing2.0 h
  • Review / QA1.0 h
9.0 hours of engineering $1,600
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,560.

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-2026-8388 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