dbcve.org
Debian LinuxOperating system · Debian

CVE-2023-3417

HIGH · 7.5 CVSS v3.1 Published 2023-07-24
Fix available
A fix is available. Upgrade to 102.13.1 / 115.0.1 or later.
See remediation →
84/100
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
Thunderbird allowed the Text Direction Override Unicode Character in filenames. An email attachment could be incorrectly shown as being a document file, while in fact it was an executable file. Newer versions of Thunderbird will strip the character and show the correct file extension. This vulnerability affects Thunderbird < 115.0.1 and Thunderbird < 102.13.1.

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

Thunderbird failed to sanitize Text Direction Override Unicode characters in attachment filenames, allowing attackers to disguise executable files (.exe, .bat, etc.) as benign document files by manipulating the displayed file extension while the actual extension remained executable.

MitigationUpdate Thunderbird to version 115.0.1 or later (ESR 115) or version 102.13.1 or later (ESR 102) to ensure the Unicode character stripping fix is applied.

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
Debian LinuxOperating system
Affected:= 10.0= 11.0= 12.0
ThunderbirdApplication
Affected:< 102.13.1>= 115.0, < 115.0.1

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
None
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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. Identify Thunderbird installation and version
    Run 'thunderbird --version' or check package manager: 'dpkg -l | grep thunderbird' (Debian) or 'rpm -qi thunderbird' (RPM-based). On Windows, check 'C:\Program Files\Mozilla Thunderbird\thunderbird.exe' properties or via Add/Remove Programs.
    Affected if Version is less than 102.13.1 OR (version >= 115.0 AND version < 115.0.1)
  2. Confirm Debian system package version
    Run 'apt-cache policy thunderbird' to see installed and available versions of the Thunderbird package.
    Affected if Installed version matches Debian 10.x, 11.x, or 12.x package versions corresponding to vulnerable Thunderbird releases
  3. Verify email attachment receipt capability
    Check if Thunderbird has any email accounts configured by inspecting profiles: look for 'prefs.js' in the profile directory (typically ~/.thunderbird/*.default/) for account configurations.
    Affected if Thunderbird is configured with email accounts capable of receiving attachments
  4. Inspect attachment filename handling (if possible)
    Create a test attachment with a filename containing Unicode directional override characters (such as U+202E RIGHT-TO-LEFT OVERRIDE) and observe if Thunderbird strips or preserves these characters when displaying the attachment in the message pane.
    Affected if Thunderbird displays the manipulated filename (showing fake extension like 'document.pdf.exe' while actual file is '.exe') without stripping the Unicode directional override characters

User is affected if Thunderbird version is below 102.13.1 or between 115.0 and 115.0.1 (exclusive), AND the application handles email attachments with filenames containing Unicode directional override characters.

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 102.13.1 / 115.0.1 or later
Fixed in 102.13.1115.0.1
Interim mitigation

Update Thunderbird to version 115.0.1 or later (ESR 115) or version 102.13.1 or later (ESR 102) to ensure the Unicode character stripping fix is applied.

Recommended fix High confidence

Thunderbird 102.13.1 or 115.0.1 and later

  1. Check current Thunderbird version by going to Help > About Thunderbird
  2. Update Thunderbird to version 102.13.1 (for Extended Support Release users) or version 115.0.1 or later (for current release users)
  3. On Linux systems, run: sudo apt update && sudo apt upgrade thunderbird (Debian/Ubuntu) or equivalent package manager update
  4. Alternatively, download the latest version from https://www.thunderbird.net/ and install manually
  5. Restart Thunderbird after update
  6. Verify the version is now 102.13.1 or higher, or 115.0.1 or higher
Caveat Security update with minimal risk; should not affect mail configuration or settings

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

Fix this in Debian Linux Scoped from the published advisory
  • Consultation6.0 h
  • Implementation4.0 h
  • Testing2.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,580
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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-2023-3417 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