---
title: "CVE-2026-92239: Thunderbird - Out of Bounds Read"
description: "Thunderbird contains an out-of-bounds read caused by a maliciously constructed IMAP line, letting attackers potentially read memory out of bounds, exploit requires crafted IMAP input."
url: https://panop.io/threat-heartbeat/CVE-2026-92239/
---

# CVE-2026-92239 Thunderbird - Out of Bounds Read

Thunderbird contains an out-of-bounds read caused by a maliciously constructed IMAP line, letting attackers potentially read memory out of bounds, exploit requires crafted IMAP input.

CVSS base score 8.1 /10

High

CISA KEV

Not listed

Public exploit

None known

Authentication

Not required

EPSS

0.41% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-92239)

## Details

Type

Out of Bounds Read

Impact

Information Disclosure

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H

Published

15 September 2026

Updated

15 October 2026

Weakness

[CWE-125](https://cwe.mitre.org/data/definitions/125.html)

## Vendor fix

Update to Thunderbird 156 or Thunderbird 140.16 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-92239](https://nvd.nist.gov/vuln/detail/CVE-2026-92239)
- [https://bugzilla.mozilla.org/show\_bug.cgi?id=2060488](https://bugzilla.mozilla.org/show_bug.cgi?id=2060488)
- [https://www.mozilla.org/security/advisories/mfsa2026-94/](https://www.mozilla.org/security/advisories/mfsa2026-94/)
- [https://www.mozilla.org/security/advisories/mfsa2026-95/](https://www.mozilla.org/security/advisories/mfsa2026-95/)
- [https://www.mozilla.org/security/advisories/mfsa2026-96/](https://www.mozilla.org/security/advisories/mfsa2026-96/)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

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