FirefoxWeb browser · Mozilla

CVE-2026-7323

HIGH · 7.3 CVSS v3.1 Published 2026-04-28

Fix available

A fix is available. Upgrade to 140.10.1 / 150.0.1 or later.

See remediation →

82/100

Remediation priority · High

Remotely reachable No privileges Zero-click

Official description

NVD · unedited

Memory safety bugs present in Thunderbird ESR 140.10.0 and Thunderbird 150.0.0. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 150.0.1, Firefox ESR 140.10.1, Thunderbird 150.0.1, and Thunderbird 140.10.1.

Technical summary

dbcve analysis · high confidence

Memory safety bugs in Thunderbird ESR 140.10.0 and Thunderbird 150.0.0 contained evidence of memory corruption that could potentially be exploited for arbitrary code execution. This was addressed in Thunderbird 140.10.1 and 150.0.1.

MitigationUpgrade Thunderbird to version 140.10.1 or 150.0.1 or later to remediate the memory corruption vulnerability.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions

NVD · CPE data

FirefoxWeb browser

Affected:< 140.10.1< 150.0.1

ThunderbirdApplication

Affected:< 140.10.1< 150.0.1

CVSS breakdown

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?

dbcve checks

Work through these to decide whether this CVE applies to you.

Check if Thunderbird is installed

Look for Thunderbird application in program directories (Windows: Program Files\Mozilla Thunderbird, macOS: /Applications/Thunderbird.app, Linux: /usr/lib/thunderbird or /opt/thunderbird)

Affected if Thunderbird is installed and its version is < 140.10.1 or == 150.0.0
Determine Thunderbird version

Open Thunderbird, go to Help > About Thunderbird, or check the application file properties

Affected if The displayed version is less than 140.10.1 OR equals 150.0.0
Check if Firefox is installed

Look for Firefox application in program directories (Windows: Program Files\Mozilla Firefox, macOS: /Applications/Firefox.app, Linux: /usr/lib/firefox or /opt/firefox)

Affected if Firefox is installed and its version is < 140.10.1 or == 150.0.0
Determine Firefox version

Open Firefox, go to Help > About Firefox, or check the application file properties

Affected if The displayed version is less than 140.10.1 OR equals 150.0.0

You are affected if Thunderbird or Firefox is installed and the version is either below 140.10.1 or exactly 150.0.0.

Generated from the published advisory. Verify against your own configuration.

Remediation

dbcve · scoped

Upgrade available Upgrade to 140.10.1 / 150.0.1 or later

Fixed in 140.10.1150.0.1

Interim mitigation

Upgrade Thunderbird to version 140.10.1 or 150.0.1 or later to remediate the memory corruption vulnerability.

Recommended fix High confidence

Firefox 150.0.1, Firefox ESR 140.10.1, Thunderbird 150.0.1, or Thunderbird 140.10.1

1. Back up any important data and settings in Firefox or Thunderbird
2. Open Firefox or Thunderbird
3. Navigate to the application menu and select 'Help' > 'About Firefox' or 'About Thunderbird'
4. The application will automatically check for updates and prompt you to download the fixed version
5. Download and install Firefox 150.0.1 (or Firefox ESR 140.10.1 for enterprise deployments) or Thunderbird 150.0.1 (or Thunderbird 140.10.1)
6. Restart the application after installation
7. Alternatively, download the latest version directly from the official Mozilla website (www.mozilla.org) and reinstall to ensure the fixed version is applied

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

Fix this in Firefox Scoped from the published advisory

Consultation1.0 h
Implementation1.0 h
Testing2.0 h
Review / QA1.0 h

5.0 hours of engineering $860

Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,376.

Scan for this in your stack

Free · runs locally

dbcve dependency scanner

Check whether your project pulls in CVE-2026-7323 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

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References

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-7323 in production — separate from our analysis above.

Notes0 Guidelines

Know something about CVE-2026-7323?

The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.

The version that genuinely resolved it — not the one the vendor claimed
A config change or rule that shut the vector down
A gotcha in the upgrade path that cost you an afternoon

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

At a glance

A fix existsUpgrade to 140.10.1 / 150.0.1 or later

Severity 7.3 High

Exploit likelihood EPSS, next 30 days 0.4%

Affects: Firefox

Remediation

A high-priority fix

Fix this in Firefox 5 hrs · Low

Typical engagement from $860

Get a fix See the full breakdown ↓

A high-priority vulnerability. Send your environment and a specialist will scope CVE-2026-7323 and return a fixed quote and timeline.

You’ll deal with our team directly and deploy the reviewed fix to staging first — never straight to production.

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.

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.

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.

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.

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.

Check your environment

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.

Scan for this in your stack

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Practitioner notes

No notes yet

Official description

Technical summary

Affected products & versions

CVSS breakdown

Am I affected?

Remediation

References