CVE-2026-126136

UNKNOWN 0.0

OAuth2 access token could be sent over an unencrypted connection with Exchange accounts

CVSS Score

0.0

EPSS Score

0.0%

EPSS Percentile

0th

For Exchange accounts using EWS or Microsoft Graph with OAuth2 authentication, Thunderbird sent the OAuth2 access token to the server even when the configured server URL used unencrypted HTTP. An attacker able to observe network traffic could obtain the token and use it to access the user's mailbox until the token expired. An attacker positioned on the network during account setup could cause such a URL to be configured. This vulnerability was fixed in Thunderbird 160 and Thunderbird 153.7.

Vendor	mozilla
Product	thunderbird
Ecosystems	Browser JavaScript
Industries	Technology
Published	Nov 10, 2026
Last Updated	Nov 10, 2026

Stay Ahead of the Next One

Get instant alerts for mozilla thunderbird

Be the first to know when new unknown vulnerabilities affecting mozilla thunderbird are published — delivered to Slack, Telegram or Discord.

Get Free Alerts → Free · No credit card · 60 sec setup

Affected Versions

Mozilla / Thunderbird

All versions affected

References

NVD ↗ CVE.org ↗ EPSS Data ↗

bugzilla.mozilla.org: https://bugzilla.mozilla.org/show_bug.cgi?id=2085865 mozilla.org: https://www.mozilla.org/security/advisories/mfsa2026-128/ mozilla.org: https://www.mozilla.org/security/advisories/mfsa2026-129/

Credits

Álvaro Chico Martínez