---
id: CVE-2026-92240
title: >-
  A malicious or compromised IMAP server can trigger an out-of-bounds read in
  the IMAP response parser by sending an untagged '* ID' response, crashing
  Thunderbird
summary: >-
  A malicious or compromised IMAP server can trigger an out-of-bounds read in
  the IMAP response parser by sending an untagged '* ID' response, crashing
  Thunderbird. The affected parsing path is reachable before authentication.
  This vulnera…
severity: critical
cvss: 9.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H'
cwe:
  - CWE-125
vendor: mozilla
product: thunderbird
affected:
  - thunderbird < 140.16.0
  - 'thunderbird >= 141.0, < 153.3.0'
  - 'thunderbird >= 154.0, < 156.0'
patched:
  - thunderbird 156.0
published: '2026-09-15'
updated: '2026-09-24'
sourceUpdated: '2026-09-24T14:15:03.237'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-92240'
references:
  - url: 'https://bugzilla.mozilla.org/show_bug.cgi?id=2069113'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-94/'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-95/'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-96/'
    label: security@mozilla.org
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-92240.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-92240'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2534187'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-92240'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-92240'
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-95/#CVE-2026-92240'
  - url: 'https://access.redhat.com/errata/RHSA-2026:70642'
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
  - score-dispute
epss: 0.00628
epssPercentile: 0.47894
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: total
  timestamp: '2026-09-22T15:41:57.658626Z'
scores:
  nvd: 9.1
  vendor: 3.4
  adp: 9.1
ingestedAt: '2026-09-15T20:44:02.609Z'
---

## Overview

A malicious or compromised IMAP server can trigger an out-of-bounds read in the IMAP response parser by sending an untagged '* ID' response, crashing Thunderbird. The affected parsing path is reachable before authentication. This vulnerability was fixed in Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.3.

## Affected

- `thunderbird < 140.16.0`
- `thunderbird >= 141.0, < 153.3.0`
- `thunderbird >= 154.0, < 156.0`

## Remediation

Upgrade past the affected range:

- `thunderbird 156.0`

## Vendor advisories

- **Red Hat VEX** · Low · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8 · updated 2026-09-24 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-92240.json)
- **RHSA-2026:70642** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 9) · released 2026-09-24 · [advisory](https://access.redhat.com/errata/RHSA-2026:70642)