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FirefoxWeb browser · Mozilla

CVE-2026-8090

HIGH · 7.3 CVSS v3.1 Published 2026-05-07
Fix available
A fix is available. Upgrade to 115.35.2 / 140.10.2 or later.
See remediation →
82/100
Remediation priority · High
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
Use-after-free in the DOM: Networking component. This vulnerability was fixed in Firefox 150.0.2, Firefox ESR 140.10.2, Firefox ESR 115.35.2, Thunderbird 150.0.2, and Thunderbird 140.10.2.

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 use-after-free vulnerability exists in the DOM networking component of Firefox and Thunderbird. This memory safety flaw allows an attacker to potentially execute arbitrary code or cause denial of service by accessing freed memory through the networking component's interaction with the DOM.

MitigationUpdate affected installations to Firefox 150.0.2, Firefox ESR 140.10.2, Firefox ESR 115.35.2, Thunderbird 150.0.2, or Thunderbird 140.10.2 as appropriate.

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:< 115.35.2< 150.0.2>= 128.0, < 140.10.2
ThunderbirdApplication
Affected:< 140.10.2< 150.0.2

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
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
Low

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

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 the installed Mozilla product
    Open the application and navigate to Help > About (Firefox or Thunderbird). The version number will be displayed in the dialog that opens.
    Affected if The product is Firefox or Thunderbird
  2. Confirm Firefox version against affected ranges
    If the product is Firefox, compare your version number to the following affected ranges: versions less than 115.35.2; versions 128.0 through 140.10.1; versions less than 150.0.2. Note that version 150.0.2 and later, and 140.10.2 and later are not affected.
    Affected if Firefox version is less than 115.35.2, or between 128.0 and 140.10.1 inclusive, or less than 150.0.2 (when considering the release channel)
  3. Confirm Thunderbird version against affected ranges
    If the product is Thunderbird, compare your version number to the affected ranges: versions less than 140.10.2 and versions less than 150.0.2. Note that versions 140.10.2 and later, and 150.0.2 and later are not affected.
    Affected if Thunderbird version is less than 140.10.2 or less than 150.0.2 (depending on the release channel being used)

You are affected if you are running Firefox with a version less than 115.35.2, between 128.0 and 140.10.1, or less than 150.0.2, or Thunderbird with a version less than 140.10.2 or less than 150.0.2.

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 115.35.2 / 140.10.2 / 150.0.2 or later
Fixed in 115.35.2140.10.2150.0.2
Interim mitigation

Update affected installations to Firefox 150.0.2, Firefox ESR 140.10.2, Firefox ESR 115.35.2, Thunderbird 150.0.2, or Thunderbird 140.10.2 as appropriate.

Recommended fix High confidence

Firefox 150.0.2, Firefox ESR 140.10.2, Firefox ESR 115.35.2, Thunderbird 150.0.2, or Thunderbird 140.10.2 (depending on current branch)

  1. Check the current Firefox or Thunderbird version (Help > About Firefox/Thunderbird)
  2. If using Firefox version 115.x (ESR), upgrade to Firefox ESR 115.35.2 or later
  3. If using Firefox version 128.x or later (but < 140.10.2), upgrade to Firefox ESR 140.10.2 or later
  4. If using Firefox version 140.x-149.x, upgrade to Firefox 150.0.2 or later
  5. If using Thunderbird version 115.x, upgrade to Thunderbird 140.10.2 or later
  6. If using Thunderbird version 128.x-139.x, upgrade to Thunderbird 140.10.2 or later
  7. If using Thunderbird version 140.x-149.x, upgrade to Thunderbird 150.0.2 or later
  8. Restart the application after upgrading
Caveat Standard Mozilla release upgrades typically have minimal breaking changes; review release notes at www.mozilla.org for add-on compatibility and feature changes

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
  • Testing3.0 h
  • Review / QA2.0 h
9.0 hours of engineering $1,570
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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-2026-8090 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