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Fencer Vulns
medium 6.5

CVE-2026-3889 json

Spoofing issue in Thunderbird

published 2026-03-24 7 mo ago modified 2026-06-17 4 mo ago also EUVD-2026-15019

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 10%
public exploits
0
none known

Summary

Spoofing issue in Thunderbird. This vulnerability was fixed in Thunderbird 149 and Thunderbird 140.9.

Patch / fix

  • mozilla thunderbird 140.9.0, 149.0
  • thunderbird Debian 12 1:140.9.0esr-1~deb12u1
  • thunderbird Debian 13 1:140.9.0esr-1~deb13u1
  • thunderbird Debian 14 1:140.9.0esr-1

debian advisories DEBIAN-CVE-2026-3889

  • thunderbird RHEL 8 140.9.0-1.el8_10
  • thunderbird RHEL 10.1 140.9.0-1.el10_1
  • thunderbird RHEL 9 140.9.0-1.el9_7
  • thunderbird RHEL 8.4 EUS_LONG_LIFE, RHEL 8.4 AUS 140.9.0-1.el8_4
  • thunderbird enterprise linux eus 10.0 140.9.0-1.el10_0
  • thunderbird RHEL 8.6 TUS, RHEL 8.6 E4S, RHEL 8.6 AUS 140.9.0-1.el8_6
  • thunderbird RHEL 9.4 EUS 140.9.0-1.el9_4
  • thunderbird RHEL 9.2 E4S 140.9.0-1.el9_2

red hat advisories RHSA-2026:8850RHSA-2026:8315RHSA-2026:8289RHSA-2026:8290RHSA-2026:8287RHSA-2026:8288

  • MozillaThunderbird openSUSE Leap 15.6 140.9.0-150200.8.263.1

suse advisories SUSE-SU-2026:1163-1

  • MozillaThunderbird openSUSE Tumbleweed 140.9.0-1.1

opensuse advisories openSUSE-SU-2026:10447-1

  • thunderbird AlmaLinux 8 140.9.0-1.el8_10.alma.1
  • thunderbird AlmaLinux 10 140.9.0-1.el10_1.alma.1
  • thunderbird AlmaLinux 9 140.9.0-1.el9_7.alma.1

almalinux advisories ALSA-2026:6917ALSA-2026:6342ALSA-2026:6188

  • thunderbird Rocky Linux 8 140.9.0-1.el8_10
  • thunderbird Rocky Linux 10 140.9.0-1.el10_1
  • thunderbird Rocky Linux 9 140.9.0-1.el9_7

rocky linux advisories RLSA-2026:6917RLSA-2026:6342RLSA-2026:6188

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-2026-3889 updated cvss 5.4

thunderbird: Spoofing issue in Thunderbird

  • Red Hat Enterprise Linux 6 thunderbird Red Hat Enterprise Linux 7 thunderbird
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 10 rhel10/thunderbird-flatpak
    affected: workaround, no fix available
  • Red Hat Enterprise Linux AppStream (v. 8) thunderbird 140.9.0-1.el8_10
    fixed: vendor fix RHSA-2026:6917
  • Red Hat Enterprise Linux AppStream (v. 9) thunderbird 140.9.0-1.el9_7
    fixed: vendor fix RHSA-2026:6188
  • Red Hat Enterprise Linux AppStream (v. 10) thunderbird 140.9.0-1.el10_1
    fixed: vendor fix RHSA-2026:6342
  • Red Hat Enterprise Linux AppStream AUS (v. 8.2) thunderbird 140.9.0-1.el8_2
    fixed: vendor fix RHSA-2026:8285
  • Red Hat Enterprise Linux AppStream AUS (v.8.4) thunderbird 140.9.0-1.el8_4
    fixed: vendor fix RHSA-2026:8850
  • Red Hat Enterprise Linux AppStream AUS (v.8.6) thunderbird 140.9.0-1.el8_6 Red Hat Enterprise Linux AppStream E4S (v.8.6) thunderbird 140.9.0-1.el8_6
    fixed: vendor fix RHSA-2026:8289
show 9 more
  • Red Hat Enterprise Linux AppStream E4S (v.8.8) thunderbird 140.9.0-1.el8_8
    fixed: vendor fix RHSA-2026:8288
  • Red Hat Enterprise Linux AppStream E4S (v.9.0) thunderbird 140.9.0-1.el9_0
    fixed: vendor fix RHSA-2026:8286
  • Red Hat Enterprise Linux AppStream E4S (v.9.2) thunderbird 140.9.0-1.el9_2
    fixed: vendor fix RHSA-2026:8287
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) thunderbird 140.9.0-1.el10_0
    fixed: vendor fix RHSA-2026:8315
  • Red Hat Enterprise Linux AppStream EUS (v.9.4) thunderbird 140.9.0-1.el9_4
    fixed: vendor fix RHSA-2026:8290
  • Red Hat Enterprise Linux AppStream EUS (v.9.6) thunderbird 140.9.0-1.el9_6
    fixed: vendor fix RHSA-2026:8284
  • Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) thunderbird 140.9.0-1.el8_4
    fixed: vendor fix RHSA-2026:8850
  • Red Hat Enterprise Linux AppStream TUS (v.8.6) thunderbird 140.9.0-1.el8_6
    fixed: vendor fix RHSA-2026:8289
  • Red Hat Enterprise Linux AppStream TUS (v.8.8) thunderbird 140.9.0-1.el8_8
    fixed: vendor fix RHSA-2026:8288

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
no
Technical impact
partial
Assessed
7 mo ago

Exploit prediction

0.21% chance of exploitation in the next 30 days, higher than 10% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
CNA 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N

Affected products

  • Mozilla Thunderbird

Classification

Weakness
  • CWE-451 User Interface (UI) Misrepresentation of Critical Information

References

Sources

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.