Medium severity5.9NVD Advisory· Published Oct 20, 2026

CVE-2026-113866

Description

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.

Affected products

Mozilla Corporation/Thunderbirdllm-fuzzy
Range: before 158.0.1 and 153.5.1

Patches

Vulnerability mechanics

References

bugzilla.mozilla.org/show_bug.cginvd
www.mozilla.org/security/advisories/mfsa2026-114/nvd
www.mozilla.org/security/advisories/mfsa2026-115/nvd

News mentions

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cvss	0.384
epss	0.000
exploit	0.000
kev	0.000
patch	0.000
ransomware	0.000