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Fencer Intel
medium 5.9

CVE-2026-113866 json

Account password sent unencrypted during Exchange account setup

published 20d ago modified 18d ago also EUVD-2026-105293

cvss
5.9
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 30%
public exploits
0
none known

Summary

When setting up an account, Thunderbird's Exchange AutoDiscover lookup also queried the domain's AutoDiscover service over plain HTTP. Due to a bug, that unencrypted request included the credentials the user had entered, allowing a network attacker to obtain the user's password. This vulnerability was fixed in Thunderbird 158.0.1 and Thunderbird 153.5.1.

Patch / fix

  • mozilla thunderbird 153.5.1, 158.0.1
  • thunderbird Debian 12 1:153.5.1esr-1~deb12u1
  • thunderbird Debian 13 1:153.5.1esr-1~deb13u1

debian advisories DEBIAN-CVE-2026-113866

  • MozillaThunderbird openSUSE Tumbleweed 153.5.1-1.1

opensuse advisories openSUSE-SU-2026:12224-1

Is CVE-2026-113866 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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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-2026-113866 updated cvss 5.3

thunderbird: thunderbird: Information disclosure via unencrypted AutoDiscover lookup

  • Red Hat Enterprise Linux 8 thunderbird, thunderbird 140.17.0-1.el10_2 Red Hat Enterprise Linux 9 thunderbird, thunderbird 140.17.0-1.el10_2 Red Hat Enterprise Linux 10 thunderbird 140.17.0-1.el10_2
    affected: no fix available “Fix deferred”

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
20d ago

Exploit prediction

0.37% chance of exploitation in the next 30 days, higher than 30% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CISA ADP 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
CNA 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Affected products

  • Mozilla Thunderbird

Classification

Weakness
  • CWE-523 Unprotected Transport of Credentials

References

Sources

Fencer Intel 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.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.