FirefoxWeb browser · Mozilla
CVE-2023-29542
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 · uneditedA newline in a filename could have been used to bypass the file extension security mechanisms that replace malicious file extensions such as .lnk with .download. This could have led to accidental execution of malicious code. *This bug only affects Firefox and Thunderbird on Windows. Other versions of Firefox and Thunderbird are unaffected.* This vulnerability affects Firefox < 112, Firefox ESR < 102.10, and Thunderbird < 102.10.
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 confidenceA newline injection vulnerability in Firefox and Thunderbird on Windows allowed attackers to bypass file extension security mechanisms. The applications attempt to sanitize downloaded filenames by replacing malicious extensions (.lnk) with .download, but a newline character in the filename could bypass this check, potentially leading to execution of malicious 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
< 112.0
Firefox EsrWeb browser
< 102.10< 102.10CVSS 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 checksWork through these to decide whether this CVE applies to you.
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Check Firefox version on WindowsOpen Firefox, click Help > About Firefox, or run 'firefox --version' from command line. Alternatively, check Add/Remove Programs or winget list to see installed Firefox version.Affected if The installed Firefox version is lower than 112.0
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Check Firefox ESR version on WindowsOpen Firefox ESR, click Help > About Firefox, or check Add/Remove Programs. Look for 'Firefox ESR' specifically - standard Firefox and Firefox ESR have separate installations.Affected if The installed Firefox ESR version is lower than 102.10
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Check Thunderbird version on WindowsOpen Thunderbird, click Help > About Thunderbird, or check Add/Remove Programs or winget list for Thunderbird installation.Affected if The installed Thunderbird version is lower than 102.10
A user is affected if they run any Mozilla Firefox (including ESR) below version 112.0 (Firefox) or 102.10 (ESR), or Thunderbird below 102.10, on Windows and download files from untrusted sources.
Generated from the published advisory. Verify against your own configuration.
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 · scoped102.10112.0
Update to Firefox 112, Firefox ESR 102.10, Thunderbird 102.10 or later. This is a client-side patch; organizations should ensure all Windows deployments are updated.
Firefox 112.0, Firefox ESR 102.10, or Thunderbird 102.10
- Upgrade Firefox to version 112.0 or later
- Upgrade Firefox ESR to version 102.10 or later
- Upgrade Thunderbird to version 102.10 or later
- Verify the installation by checking Help > About Firefox or Help > About Thunderbird
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Firefox
Scoped from the published advisory
- Consultation1.0 h
- Implementation2.0 h
- Testing1.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,424.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2023-29542 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2023-29542 in production — separate from our analysis above.
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
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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.
- 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