CVE-2026-113866
Account password sent unencrypted during Exchange account setup
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- None
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
Account password sent unencrypted during Exchange account setup
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.
- Record
CVE-2026-113866- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N - Weakness
- CWE-523
- Updated
- 2026-11-02
EUVDEUVD-2026-105293
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.
- Record
EUVD-2026-105293- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-6c7w-fhrm-qhj3
When setting up an account, Thunderbird's Exchange AutoDiscover lookup also queried the domain's...
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.
- Record
GHSA-6c7w-fhrm-qhj3- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N - Weakness
- CWE-523
- Updated
- 2026-11-02
NVD
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.
- Record
CVE-2026-113866- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N - Weakness
- CWE-523
- Updated
- 2026-11-02
OSVDEBIAN-CVE-2026-113866
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.
- Record
DEBIAN-CVE-2026-113866- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N - Updated
- 2026-11-02
OSVUBUNTU-CVE-2026-113866
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.
- Record
UBUNTU-CVE-2026-113866- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N - Updated
- 2026-11-02
OSVopenSUSE-SU-2026:12224-1 No score
MozillaThunderbird-153.5.1-1.1 on GA media
These are all security issues fixed in the MozillaThunderbird-153.5.1-1.1 package on the GA media of openSUSE Tumbleweed.
- Record
openSUSE-SU-2026:12224-1- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
thunderbirdDebian:12 |
before 1:153.5.1esr-1~deb12u1, plus listed versions 1:102.11.0-11:102.12.0-11:102.12.0-1~deb10u11:102.12.0-1~deb11u11:102.12.0-1~deb12u1 Show 45 moreShow less1:102.13.0-11:102.13.0-1~deb10u11:102.13.0-1~deb11u11:102.13.0-1~deb12u11:102.13.1-11:102.13.1-1~deb10u11:102.13.1-1~deb11u11:102.13.1-1~deb12u11:102.14.0-1~deb10u11:102.14.0-1~deb11u11:102.14.0-1~deb12u11:102.15.0-1~deb10u11:102.15.0-1~deb11u11:102.15.0-1~deb12u11:102.15.1-1~deb10u11:102.15.1-1~deb11u11:102.15.1-1~deb12u11:103.0~b5-11:104.0~b2-11:110.0~b4-11:112.0~b1-11:113.0~b3-11:114.0~b2-11:115.0-11:115.0.1-11:115.0.1-21:115.0~b4-11:115.0~b6-11:115.1.0-11:115.1.1-11:115.10.1-11:115.10.1-1~deb10u11:115.10.1-1~deb11u11:115.10.1-1~deb12u11:115.11.0-11:115.11.0-1~deb10u11:115.11.0-1~deb11u11:115.11.0-1~deb12u11:115.12.0-11:115.12.0-1~deb10u11:115.12.0-1~deb11u11:115.12.0-1~deb12u11:115.13.0-11:115.13.0-1~deb11u11:115.13.0-1~deb12u1 |
1:153.5.1esr-1~deb12u1 |
thunderbirdDebian:13 |
before 1:153.5.1esr-1~deb13u1, plus listed versions 1:128.13.0esr-11:128.14.0esr-11:128.14.0esr-1~deb11u11:128.14.0esr-1~deb12u11:128.14.0esr-1~deb13u1 Show 45 moreShow less1:129.0~b6-11:130.0~b3-11:132.0~b6-11:135.0-11:136.0-11:137.0-11:138.0-11:140.0.1esr-11:140.1.0esr-11:140.1.1esr-11:140.10.0esr-11:140.10.0esr-1~deb11u11:140.10.0esr-1~deb12u11:140.10.0esr-1~deb13u11:140.10.1esr-11:140.10.1esr-1~deb11u11:140.10.1esr-1~deb12u11:140.10.1esr-1~deb13u11:140.10.2esr-11:140.10.2esr-1~deb11u11:140.10.2esr-1~deb12u11:140.10.2esr-1~deb13u11:140.11.0esr-11:140.11.0esr-1~deb11u11:140.11.0esr-1~deb12u11:140.11.0esr-1~deb13u11:140.12.0esr-11:140.12.0esr-1~deb11u11:140.12.0esr-1~deb12u11:140.12.0esr-1~deb13u11:140.13.0esr-11:140.13.0esr-21:140.13.0esr-2~deb11u11:140.13.0esr-2~deb12u11:140.13.0esr-2~deb13u11:140.14.0esr-11:140.14.0esr-1~deb11u11:140.14.0esr-1~deb12u11:140.14.0esr-1~deb13u11:140.15.0esr-1~deb12u11:140.15.0esr-1~deb13u11:140.16.0esr-1~deb12u11:140.16.0esr-1~deb13u11:140.17.0esr-1~deb12u11:140.17.0esr-1~deb13u1 |
1:153.5.1esr-1~deb13u1 |
thunderbirdDebian:14 |
All versions, plus listed versions 1:128.13.0esr-11:128.14.0esr-11:128.14.0esr-1~deb11u11:128.14.0esr-1~deb12u11:128.14.0esr-1~deb13u1 Show 45 moreShow less1:129.0~b6-11:130.0~b3-11:132.0~b6-11:135.0-11:136.0-11:137.0-11:138.0-11:140.0.1esr-11:140.1.0esr-11:140.1.1esr-11:140.10.0esr-11:140.10.0esr-1~deb11u11:140.10.0esr-1~deb12u11:140.10.0esr-1~deb13u11:140.10.1esr-11:140.10.1esr-1~deb11u11:140.10.1esr-1~deb12u11:140.10.1esr-1~deb13u11:140.10.2esr-11:140.10.2esr-1~deb11u11:140.10.2esr-1~deb12u11:140.10.2esr-1~deb13u11:140.11.0esr-11:140.11.0esr-1~deb11u11:140.11.0esr-1~deb12u11:140.11.0esr-1~deb13u11:140.12.0esr-11:140.12.0esr-1~deb11u11:140.12.0esr-1~deb12u11:140.12.0esr-1~deb13u11:140.13.0esr-11:140.13.0esr-21:140.13.0esr-2~deb11u11:140.13.0esr-2~deb12u11:140.13.0esr-2~deb13u11:140.14.0esr-11:140.14.0esr-1~deb11u11:140.14.0esr-1~deb12u11:140.14.0esr-1~deb13u11:140.15.0esr-1~deb12u11:140.15.0esr-1~deb13u11:140.16.0esr-1~deb12u11:140.16.0esr-1~deb13u11:140.17.0esr-1~deb12u11:140.17.0esr-1~deb13u1 |
None known |
thunderbirdUbuntu:22.04:LTS |
All versions, plus listed versions 1:91.1.2+build1-0ubuntu11:91.3.0+build2-0ubuntu11:91.3.1+build1-0ubuntu11:91.3.2+build1-0ubuntu11:91.4.0+build1.1-0ubuntu1 Show 34 moreShow less1:91.4.0+build2-0ubuntu11:91.5.0+build1-0ubuntu11:91.5.1+build1-0ubuntu11:91.6.1+build1-0ubuntu11:91.7.0+build1-0ubuntu11:91.7.0+build2-0ubuntu11:91.8.0+build2-0ubuntu11:91.9.1+build1-0ubuntu0.22.04.11:91.11.0+build2-0ubuntu0.22.04.11:102.2.2+build1-0ubuntu0.22.04.11:102.4.2+build2-0ubuntu0.22.04.11:102.7.1+build2-0ubuntu0.22.04.11:102.8.0+build2-0ubuntu0.22.04.11:102.9.0+build1-0ubuntu0.22.04.11:102.10.0+build2-0ubuntu0.22.04.11:102.11.0+build1-0ubuntu0.22.04.11:102.13.0+build1-0ubuntu0.22.04.11:102.15.0+build1-0ubuntu0.22.04.11:102.15.1+build1-0ubuntu0.22.04.11:115.3.1+build1-0ubuntu0.22.04.21:115.4.1+build1-0ubuntu0.22.04.11:115.5.0+build1-0ubuntu0.22.04.11:115.6.0+build2-0ubuntu0.22.04.11:115.8.1+build1-0ubuntu0.22.04.11:115.9.0+build1-0ubuntu0.22.04.11:115.10.1+build1-0ubuntu0.22.04.11:115.11.0+build2-0ubuntu0.22.04.11:115.12.0+build3-0ubuntu0.22.04.11:115.13.0+build5-0ubuntu0.22.04.11:115.15.0+build1-0ubuntu0.22.04.11:115.16.0+build2-0ubuntu0.22.04.11:115.18.0+build1-0ubuntu0.22.04.11:128.12.0+build1-0ubuntu0.22.04.11:140.7.1+build1-0ubuntu0.22.04.1 |
None known |
thunderbirdUbuntu:24.04:LTS |
All versions, plus listed versions 1:115.3.1+build1-0ubuntu11:115.4.1+build1-0ubuntu11:115.4.3+build1-0ubuntu11:115.5.0+build1-0ubuntu11:115.5.1+build1-0ubuntu1 Show 9 moreShow less1:115.5.2+build2-0ubuntu11:115.6.0+build1-0ubuntu11:115.6.0+build2-0ubuntu11:115.6.1+build1-0ubuntu11:115.8.0+build1-0ubuntu11:115.8.1+build1+snap21:115.8.1+build1+snap32:1snap1-0ubuntu12:1snap1-0ubuntu3 |
None known |
thunderbirdUbuntu:26.10 |
All versions, plus listed versions 2:1snap1-0ubuntu5 |
None known |
thunderbirdUbuntu:26.04:LTS |
All versions, plus listed versions 2:1snap1-0ubuntu32:1snap1-0ubuntu42:1snap1-0ubuntu5 |
None known |
MozillaThunderbirdopenSUSE:Tumbleweed From an advisory covering 66 CVEs |
before 153.5.1-1.1 | 153.5.1-1.1 |
History
| Recorded | Changed | Sources |
|---|---|---|
| affected, facts | ||
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-113866 is a medium vulnerability (CVSS 5.9) in Mozilla Thunderbird, published October 20, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.36%, the 30th percentile. Fixed in thunderbird 1:153.5.1esr-1~deb12u1.
References
bugzilla.mozilla.org/show_bug.cgi?id=2080121
mozilla.org/security/advisories/mfsa2026-114
nvd.nist.gov/vuln/detail/CVE-2026-113866
github.com/advisories/GHSA-6c7w-fhrm-qhj3
security-tracker.debian.org/tracker/CVE-2026-113866
Show 69 moreShow less
ubuntu.com/security/CVE-2026-113866
cve.org/CVERecord?id=CVE-2026-113866
suse.com/security/cve/CVE-2026-109704
Left out here: 305 versions. The JSON record has them.