CVE-2026-92238: Ambiguous parsing of mail headers

Published Sep 15, 2026
·
Updated

A maliciously constructed mail header could lead to multiple fields being parsed as one, or potential memory safety violations.

Affected Software

3 affected componentsFixes available
Mozilla Thunderbird=140.16
Mozilla Thunderbird<156
156
Mozilla Thunderbird<140.16
140.16

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 156
  2. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 140.16
  3. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 140.16Patch Thunderbird 140.16

Event History

Sep 15, 2026
CVE Published
via Mozilla·12:00 AM
Data Sourced
via Mozilla·12:00 AM
DescriptionSeverityAffected Software
Updated
via Mozilla·12:00 AM
Affected Software
CVE Published
via MITRE·07:42 PM
Data Sourced
via MITRE·07:42 PM
Description

Parent advisories

This vulnerability appears in the following advisories.

Peer vulnerabilities

Found alongside the following vulnerabilities.

Frequently Asked Questions

1

What does an attacker need to exploit this issue?

An attacker needs to provide a maliciously constructed mail header that triggers ambiguous parsing.

2

Which Thunderbird release contains the fix?

The vulnerability was fixed in Thunderbird 140.16.

Company

Resources

Contact

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