critical 9.1

CVE-2026-92240 json

Out-of-bounds read in IMAP response parser

published 2026-09-15 54 d ago modified 2026-09-24 45 d ago also EUVD-2026-79244

cvss: 9.1; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.6%; EPSS 0.6% chance of exploitation in 30 days, percentile 50%
public exploits: 0; none known

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.

Patch / fix

fixed in 1 distros 6

mozilla thunderbird 140.16.0, 153.3.0, 156.0

debian red hat suse opensuse almalinux rocky linux

thunderbird Debian 12 1:140.16.0esr-1~deb12u1
thunderbird Debian 13 1:140.16.0esr-1~deb13u1
thunderbird Debian 14 1:153.3.0esr-1

debian advisories DEBIAN-CVE-2026-92240

thunderbird RHEL 8 140.16.0-1.el8_10
thunderbird RHEL 10.2 140.16.0-1.el10_2
thunderbird RHEL 9 140.16.0-1.el9_8
thunderbird RHEL 8.4 EUS_LONG_LIFE, RHEL 8.4 AUS 140.16.0-1.el8_4
thunderbird RHEL 8.6 EUS_LONG_LIFE, RHEL 8.6 AUS 140.16.0-1.el8_6
thunderbird RHEL 9.6 EUS 140.16.0-1.el9_6
thunderbird RHEL 8.8 TUS, RHEL 8.8 E4S 140.16.0-1.el8_8
thunderbird RHEL 9.2 E4S 140.16.0-1.el9_2

red hat advisories RHSA-2026:82122 RHSA-2026:81913 RHSA-2026:81884 RHSA-2026:81912 RHSA-2026:81394 RHSA-2026:81393

MozillaThunderbird SLE Workstation Extension 15 SP7, SLE Module for Package Hub 15 SP7 153.4.0-150400.13.6.1

suse advisories SUSE-SU-2026:4627-1

MozillaThunderbird openSUSE Tumbleweed 140.16.0-1.1

opensuse advisories openSUSE-SU-2026:11827-1

thunderbird AlmaLinux 8 140.16.0-1.el8_10.alma.1
thunderbird AlmaLinux 10 140.16.0-1.el10_2.alma.1
thunderbird AlmaLinux 9 140.16.0-1.el9_8.alma.1

almalinux advisories ALSA-2026:73971 ALSA-2026:73130 ALSA-2026:70642

thunderbird Rocky Linux 8 140.16.0-1.el8_10
thunderbird Rocky Linux 10 140.16.0-1.el10_2
thunderbird Rocky Linux 9 140.16.0-1.el9_8

rocky linux advisories RLSA-2026:73971 RLSA-2026:73130 RLSA-2026:70642

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-92240 updated 2026-11-07 cvss 3.4

thunderbird: Out-of-bounds read in IMAP response parser

Red Hat Enterprise Linux 6 thunderbird Red Hat Enterprise Linux 7 thunderbird
affected: no fix planned “Out of support scope”
Red Hat Enterprise Linux 10 rhel10/thunderbird-flatpak
affected: no fix available
Red Hat Enterprise Linux AppStream (v. 8) thunderbird 140.16.0-1.el8_10
fixed: vendor fix RHSA-2026:73971
Red Hat Enterprise Linux AppStream (v. 9) thunderbird 140.16.0-1.el9_8
fixed: vendor fix RHSA-2026:70642
Red Hat Enterprise Linux AppStream (v. 10) thunderbird 140.16.0-1.el10_2
fixed: vendor fix RHSA-2026:73130
Red Hat Enterprise Linux AppStream AUS (v.8.4) thunderbird 140.16.0-1.el8_4
fixed: vendor fix RHSA-2026:82122
Red Hat Enterprise Linux AppStream AUS (v.8.6) thunderbird 140.16.0-1.el8_6
fixed: vendor fix RHSA-2026:81913
Red Hat Enterprise Linux AppStream E4S (v.8.8) thunderbird 140.16.0-1.el8_8
fixed: vendor fix RHSA-2026:81912

show 7 more

Red Hat Enterprise Linux AppStream E4S (v.9.2) thunderbird 140.16.0-1.el9_2
fixed: vendor fix RHSA-2026:81394
Red Hat Enterprise Linux AppStream E4S (v.9.4) thunderbird 140.16.0-1.el9_4
fixed: vendor fix RHSA-2026:81393
Red Hat Enterprise Linux AppStream EUS (v. 10.0) thunderbird 140.16.0-1.el10_0
fixed: vendor fix RHSA-2026:81392
Red Hat Enterprise Linux AppStream EUS (v.9.6) thunderbird 140.16.0-1.el9_6
fixed: vendor fix RHSA-2026:81884
Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) thunderbird 140.16.0-1.el8_4
fixed: vendor fix RHSA-2026:82122
Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6) thunderbird 140.16.0-1.el8_6
fixed: vendor fix RHSA-2026:81913
Red Hat Enterprise Linux AppStream TUS (v.8.8) thunderbird 140.16.0-1.el8_8
fixed: vendor fix RHSA-2026:81912

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation: none
Automatable: yes
Technical impact: total
Assessed: 47 d ago (2026-09-22)

Exploit prediction

0.63% chance of exploitation in the next 30 days, higher than 50% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CISA ADP	3.1	9.1	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
CNA	3.1	9.1	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

Affected products

Mozilla Thunderbird

Classification

Weakness

CWE-125 Out-of-bounds Read

References

mozilla.org /security/advisories/mfsa2026-94/
vendor-advisory
mozilla.org /security/advisories/mfsa2026-95/
vendor-advisory
mozilla.org /security/advisories/mfsa2026-96/
vendor-advisory
bugzilla.mozilla.org /show_bug.cgi?id=2069113
permissions-required

Sources

CVE List CVE-2026-92240
NVD CVE-2026-92240

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary