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CVE Record

CVE-2023-3417: File Extension Spoofing using the Text Direction Override Character

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.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

Thunderbird could make a malicious email attachment look like a document when it was actually an executable. The issue used a Unicode text-direction character to confuse filename display. Business risk is mainly phishing-driven execution by users on outdated Thunderbird versions.

Executive priority

Prioritize as a routine but real phishing-resilience fix. It is not documented as actively exploited in the supplied sources, but outdated clients can make malicious attachments appear safer than they are.

Technical view

Thunderbird allowed the Text Direction Override Unicode character in attachment filenames. This could cause the displayed filename extension to differ from the real executable extension. Mozilla states newer Thunderbird versions strip the character and show the correct extension. Affected versions are Thunderbird before 115.0.1 and before 102.13.1.

Likely exposure

Exposure is limited to organizations with Thunderbird installations older than 115.0.1 or 102.13.1, especially users who receive and open email attachments. Debian-packaged Thunderbird users should review the Debian security advisories for applicable fixed packages.

Exploitation context

The provided sources do not show CISA KEV listing or active exploitation. Practical abuse would likely require a user receiving a crafted attachment and trusting the misleading displayed filename. Evidence for exploit prevalence is incomplete in the provided bundle.

Researcher notes

This is a UI filename-spoofing vulnerability, not a remote code execution claim by itself. Key validation is version exposure and attachment-handling workflow. The source bundle lacks CVSS, CWE, and detailed exploitability metrics, so risk should be contextualized by user interaction and mail controls.

Mitigation direction

  • Upgrade Thunderbird to 115.0.1 or later, or 102.13.1 or later.
  • Apply Debian DSA-5463 or Debian LTS Thunderbird updates where applicable.
  • Review Mozilla advisories MFSA2023-27 and MFSA2023-28 for vendor guidance.
  • Keep mail attachment controls aligned to block or warn on executable attachments.

Validation and detection

  • Inventory Thunderbird versions across endpoints and managed images.
  • Confirm no deployed Thunderbird version is earlier than 115.0.1 or 102.13.1.
  • Check Debian hosts for the Thunderbird security update referenced in DSA-5463.
  • Review mail security logs for executable attachment handling and user-reported suspicious attachments.
Prepared
Confidence
high
Sources
7

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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CVE-2023-3417 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
0Timeline events
0ADP providers
6Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
MozillaThunderbirdunspecifiedListed
MozillaThunderbirdunspecifiedListed
Weakness

CWE details

No CWE listed

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