What’s Vulnerable › Vulnerabilities

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

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2023-07-24 · updated 2026-06-17

Description

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.

Affected products

• Debian Linux: 10.0, 11.0, 12.0
• Mozilla Thunderbird: before 102.13.1; from 115.0 before 115.0.1 — fixed in 102.13.1, 115.0.1

How to fix

Upgrade to a fixed version: Mozilla Thunderbird 102.13.1, 115.0.1. Check the vendor advisory for mitigations.

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=1835582
• https://lists.debian.org/debian-lts-announce/2023/07/msg00032.html
• https://www.debian.org/security/2023/dsa-5463
• https://www.mozilla.org/security/advisories/mfsa2023-27/
• https://www.mozilla.org/security/advisories/mfsa2023-28/
• https://bugzilla.mozilla.org/show_bug.cgi?id=1835582
• https://lists.debian.org/debian-lts-announce/2023/07/msg00032.html
• https://www.debian.org/security/2023/dsa-5463
• https://www.mozilla.org/security/advisories/mfsa2023-27/
• https://www.mozilla.org/security/advisories/mfsa2023-28/

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