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FirefoxWeb browser · Mozilla

CVE-2026-16360

CRITICAL · 9.8 CVSS v3.1 Developing Published 2026-07-21
Fix available
A fix is available. Upgrade to 115.38.0 / 140.13.0 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click 4 weeks old

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
Memory safety bugs present in Firefox ESR 115.37, Firefox ESR 140.12 and Firefox 152. 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 153, Firefox ESR 115.38, Firefox ESR 140.13, Thunderbird 153, and Thunderbird 140.13.

In the news

Third-party coverage
Trending covered by 1 outlet this week · latest today

Surfaced from public web coverage — external links open in a new tab.

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 · low confidence
Developing — this CVE was published recently and its authoritative NVD entry is still being established, so we're holding a technical summary until the source data settles rather than publish something unreliable. Re-checking after 2026-08-04.

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:< 115.38.0< 153.0.0>= 128.1.0, < 140.13.0
ThunderbirdApplication
Affected:< 140.13.0>= 141.0, < 153.0

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

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 115.38.0 / 140.13.0 / 153.0 or later
Fixed in 115.38.0140.13.0153.0
Recommended fix High confidence

Thunderbird 140.13 or Thunderbird 153

  1. 1. Close Thunderbird if it is currently running
  2. 2. Verify current Thunderbird version by going to Help > About Thunderbird
  3. 3. Download Thunderbird 140.13 or Thunderbird 153 from the official Mozilla Thunderbird website (www.thunderbird.net)
  4. 4. Run the installer and follow the prompts to upgrade
  5. 5. Restart Thunderbird after the upgrade completes
  6. 6. Verify the new version by checking Help > About Thunderbird to confirm the version number matches 140.13 or 153
Caveat Minor: Some legacy extension compatibility may be affected; review extension compatibility if using older add-ons

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

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $3,550. Get the upgrade done

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-2026-16360 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