dbcve.org
FirefoxWeb browser · Mozilla

CVE-2026-2773

CRITICAL · 9.8 CVSS v3.1 Published 2026-02-24
Fix available
A fix is available. Upgrade to 115.33.0 / 140.8.0 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
Incorrect boundary conditions in the Web Audio component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

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

A boundary condition vulnerability exists in the Web Audio component of Firefox and Thunderbird. Incorrect boundary checks can lead to memory corruption, potentially allowing remote code execution or sandbox escape.

MitigationUpdate affected installations to Firefox 148, Firefox ESR 115.33/140.8, or Thunderbird 148/140.8 as appropriate. For systems that cannot be immediately updated, consider restricting Web Audio API usage or additional network-level controls.

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:< 115.33.0< 148.0>= 128.0, < 140.8.0
ThunderbirdApplication
Affected:< 140.8.0< 148.0

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:3.1/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 Mozilla Firefox is installed
    On Windows, check for Firefox in C:\Program Files\Mozilla Firefox or via 'Get-ItemProperty HKLM:\Software\Mozilla\Mozilla Firefox' in PowerShell. On macOS, check /Applications/Firefox.app. On Linux, run 'which firefox' or check package manager.
    Affected if Firefox is installed and version is less than 115.33.0, or between 128.0 and 140.7.x inclusive, or less than 148.0 with version >= 128.0 but less than 140.8.0 (check against all affected ranges)
  2. Determine installed Firefox version
    On Windows, go to Help > About Firefox or run 'firefox --version' in command prompt. On macOS, right-click Firefox in Applications > Get Info or run 'firefox --version' in Terminal. On Linux, run 'firefox --version'.
    Affected if The version number returned falls outside the safe versions: 115.33.0 and newer, 140.8.0 and newer, or 148.0 and newer
  3. Check if Thunderbird is installed
    On Windows, check for Thunderbird in C:\Program Files\Mozilla Thunderbird or via registry. On macOS, check /Applications/Thunderbird.app. On Linux, run 'which thunderbird' or check package manager.
    Affected if Thunderbird is installed and version is less than 140.8.0, or less than 148.0 (check against affected ranges)
  4. Determine installed Thunderbird version
    On Windows, go to Help > About Thunderbird or run 'thunderbird --version' in command prompt. On macOS, right-click Thunderbird in Applications > Get Info or run 'thunderbird --version' in Terminal. On Linux, run 'thunderbird --version'.
    Affected if The version number returned falls outside the safe versions: 140.8.0 and newer, or 148.0 and newer

You are affected if any installed Firefox version is below 115.33.0, between 128.0 and 140.7.x, or any Thunderbird version is below 140.8.0 (or below 148.0 depending on the specific branch).

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 115.33.0 / 140.8.0 / 148.0 or later
Fixed in 115.33.0140.8.0148.0
Interim mitigation

Update affected installations to Firefox 148, Firefox ESR 115.33/140.8, or Thunderbird 148/140.8 as appropriate. For systems that cannot be immediately updated, consider restricting Web Audio API usage or additional network-level controls.

Recommended fix High confidence

Firefox 148.0+, Firefox ESR 115.33+, Firefox ESR 140.8+, Thunderbird 148.0+, or Thunderbird 140.8+

  1. Identify the current Firefox or Thunderbird version by navigating to Menu > Help > About [Application Name]
  2. For Firefox users on standard release: upgrade to Firefox 148.0 or later
  3. For Firefox users on ESR 128.x: upgrade to Firefox ESR 140.8 or later
  4. For Firefox users on ESR 115.x: upgrade to Firefox ESR 115.33 or later
  5. For Thunderbird users on standard release: upgrade to Thunderbird 148.0 or later
  6. For Thunderbird users on ESR: upgrade to Thunderbird 140.8 or later
  7. Restart the application after upgrading
  8. Verify the version by checking Menu > Help > About to confirm the upgrade was successful
Caveat Users on extended support releases should verify that their organization's IT policies allow updating to these specific ESR versions before deploying

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
  • Testing3.0 h
  • Review / QA1.0 h
10.0 hours of engineering $1,750
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,800.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2026-2773 — 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-2026-2773 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