Alinto
SOGo before 5.12.13 Missing Rate Limiting on TOTP Verification
Not on CISA's list of exploited flaws, and not in the news we track.
CVE-2026-127131Critical9.1
Black Shard's team can check your exposure to CVE-2026-127131 and take the fix off your plate.
SOGo before 5.12.13 contains a missing rate limiting vulnerability in its web login TOTP verification that allows attackers who already possess a victim's password to brute-force the second-factor code without triggering any lockout. Attackers can send repeated POST requests to /SOGo/connect with wrong verification codes at high speed since failed TOTP attempts never increment the failed-login counter and SOGoMaximumFailedLoginCount does not apply, enabling indefinite guessing across 30-second code windows to bypass two-factor authentication.
Black Shard's team can check your exposure, take a fix off your plate or step in on a live incident.
Severity
9.1of 10, critical
Updated 13 Nov 2026, 12:02 UTC, 30 of 36 sources answering.
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