CVE-2026-118175: Content of other messages could be included when replying to a crafted message

Published Oct 27, 2026
·
Updated

When replying to, forwarding, or editing a crafted email message as new, Thunderbird could embed parts of a different message stored in the same folder into the message being composed, without showing a blocked content warning. If the user sent the message, the content of the other message was disclosed to the recipients.

Affected Software

2 affected componentsFixes available
Mozilla Thunderbird<159
159
Mozilla Thunderbird<153.6
153.6

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 159
  2. Upgrade

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

    Fixed in 153.6
  3. Upgrade

    Upgrade Thunderbird to a version that resolves this vulnerability.

    Fixed in 159

Event History

Oct 27, 2026
CVE Published
via Mozilla·12:00 AM
Data Sourced
via Mozilla·12:00 AM
DescriptionSeverityAffected Software
CVE Published
via MITRE·06:16 PM
Data Sourced
via MITRE·06:16 PM
Description

Parent advisories

This vulnerability appears in the following advisories.

Peer vulnerabilities

Found alongside the following vulnerabilities.

Frequently Asked Questions

1

What user action is required for information to be disclosed?

A user must reply to, forward, or edit a crafted email message as new, and then send the resulting message. The disclosure occurs only if the composed message is sent to recipients.

2

What information could be exposed?

Parts of a different message stored in the same folder as the crafted message could be embedded in the outgoing message. The user would not receive a blocked content warning for this inclusion.

3

Which installations are affected?

Thunderbird versions before 159 are affected based on the available fix information. Updating to Thunderbird 159 addresses the vulnerability.

Company

Resources

Contact

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