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FirefoxWeb browser · Mozilla

CVE-2024-6603

HIGH · 7.4 CVSS v3.1 Published 2024-07-09
Fix available
A fix is available. Upgrade to 115.13 / 128.0 or later.
See remediation →
83/100
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
In an out-of-memory scenario an allocation could fail but free would have been called on the pointer afterwards leading to memory corruption. This vulnerability affects Firefox < 128, Firefox ESR < 115.13, Thunderbird < 115.13, and Thunderbird < 128.

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 memory corruption vulnerability exists in Firefox and Thunderbird where an out-of-memory allocation failure still results in a subsequent free() call on the same pointer, leading to use-after-free or double-free conditions that can be exploited for code execution.

MitigationUpdate to Firefox 128+, Firefox ESR 115.13+, or Thunderbird 115.13+/128+ to patch the vulnerable memory handling code.

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:< 115.13< 128.0
ThunderbirdApplication
Affected:< 115.13>= 116.0, < 128.0

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
High
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/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. Determine installed Firefox version
    Open Firefox, go to Help > About Firefox, or run 'firefox --version' from command line. Also check /Applications/Firefox.app/Contents/Info.plist on macOS or rpm -q firefox / dpkg -l firefox on Linux.
    Affected if Version is less than 128.0 (or specifically less than 115.13)
  2. Determine installed Thunderbird version
    Open Thunderbird, go to Help > About Thunderbird, or run 'thunderbird --version' from command line. Also check /Applications/Thunderbird.app/Contents/Info.plist on macOS or rpm -q thunderbird / dpkg -l thunderbird on Linux.
    Affected if Version is less than 115.13, OR version is 116.0 or higher but less than 128.0 (versions 115.13 through 115.x are not affected)
  3. Verify vulnerability condition applies
    This is a memory handling bug that triggers during out-of-memory allocation failure scenarios. The flaw exists in the underlying memory allocation code regardless of specific configurations - if the affected version is running, the vulnerable code path is present.
    Affected if The installed Firefox version is below 128.0, or the installed Thunderbird version is below 115.13 or between 116.0 and 127.x

You are affected if running any version of Firefox below 128.0, or any version of Thunderbird below 115.13 or between 116.0 and 127.x.

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 115.13 / 128.0 or later
Fixed in 115.13128.0
Interim mitigation

Update to Firefox 128+, Firefox ESR 115.13+, or Thunderbird 115.13+/128+ to patch the vulnerable memory handling code.

Recommended fix High confidence

Firefox 128.0 / Firefox ESR 115.13 / Thunderbird 128.0 / Thunderbird 115.13

  1. 1. Check current Firefox version by navigating to Menu > Help > About Firefox
  2. 2. Check current Thunderbird version by navigating to Menu > Help > About Thunderbird
  3. 3. If using Firefox < 128.0, upgrade to Firefox 128.0 or later
  4. 4. If using Firefox ESR < 115.13, upgrade to Firefox ESR 115.13 or later
  5. 5. If using Thunderbird < 115.13, upgrade to Thunderbird 115.13 or later
  6. 6. If using Thunderbird >= 116.0 and < 128.0, upgrade to Thunderbird 128.0 or later
  7. 7. Restart the application after upgrade
Caveat Users on extended support releases should migrate to the latest ESR version; standard release users should upgrade to 128.0

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
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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-2024-6603 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