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Fencer Vulns
medium 5.9

CVE-2020-15646 json

If an attacker intercepts Thunderbird's initial attempt to perform automatic account setup using the Microsoft Exchange autodiscovery mecha…

published 2020-10-08 6 y ago modified 2026-06-17 4 mo ago also EUVD-2020-7633

cvss
5.9
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.0%
EPSS 1.0% chance of exploitation in 30 days, percentile 61%
public exploits
0
none known

Summary

If an attacker intercepts Thunderbird's initial attempt to perform automatic account setup using the Microsoft Exchange autodiscovery mechanism, and the attacker sends a crafted response, then Thunderbird sends username and password over https to a server controlled by the attacker. This vulnerability affects Thunderbird < 68.10.0.

Patch / fix

  • Mozilla Thunderbird 68.10.0
  • thunderbird Debian 14, Debian 13, Debian 12 1:68.10.0-1

debian advisories DEBIAN-CVE-2020-15646

  • thunderbird Ubuntu 16.04 LTS 1:68.10.0+build1-0ubuntu0.16.04.1
  • thunderbird Ubuntu 18.04 LTS 1:68.10.0+build1-0ubuntu0.18.04.1
  • thunderbird Ubuntu 20.04 LTS 1:68.10.0+build1-0ubuntu0.20.04.1

ubuntu advisories UBUNTU-CVE-2020-15646

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • thunderbird RHEL 8 68.10.0-1.el8_2
  • thunderbird RHEL 6 68.10.0-1.el6_10
  • thunderbird RHEL 7 68.10.0-1.el7_8
  • thunderbird RHEL 8.0 E4S 68.10.0-1.el8_0
  • thunderbird RHEL 8.1 EUS 68.10.0-1.el8_1

red hat advisories RHSA-2020:3046RHSA-2020:3038RHSA-2020:2966RHSA-2020:2907RHSA-2020:2906

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-2020-15646 updated cvss 5.9

Mozilla: Automatic account setup leaks Microsoft Exchange login credentials

  • Red Hat Enterprise Linux 5 thunderbird
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux AppStream (v. 8) thunderbird 68.10.0-1.el8_2
    fixed: vendor fix RHSA-2020:3038
  • Red Hat Enterprise Linux AppStream E4S (v. 8.0) thunderbird 68.10.0-1.el8_0
    fixed: vendor fix RHSA-2020:3046
  • Red Hat Enterprise Linux AppStream EUS (v. 8.1) thunderbird 68.10.0-1.el8_1
    fixed: vendor fix RHSA-2020:2907
  • Red Hat Enterprise Linux Client (v. 7) thunderbird 68.10.0-1.el7_8
    fixed: vendor fix RHSA-2020:2906
  • Red Hat Enterprise Linux Desktop (v. 6) thunderbird 68.10.0-1.el6_10 Red Hat Enterprise Linux Server Optional (v. 6) thunderbird 68.10.0-1.el6_10
    fixed: vendor fix RHSA-2020:2966
  • Red Hat Enterprise Linux Server Optional (v. 7) thunderbird 68.10.0-1.el7_8
    fixed: vendor fix RHSA-2020:2906
  • Red Hat Enterprise Linux Workstation (v. 6) thunderbird 68.10.0-1.el6_10
    fixed: vendor fix RHSA-2020:2966
show 1 more
  • Red Hat Enterprise Linux Workstation (v. 7) thunderbird 68.10.0-1.el7_8
    fixed: vendor fix RHSA-2020:2906

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

Exploit prediction

0.96% chance of exploitation in the next 30 days, higher than 61% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:P/I:N/A:N

Affected products

  • Mozilla Thunderbird

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.