Sources: National Vulnerability Database, CVE.org, CISA KEV, FIRST EPSS
CVE-2026-127131 Overview
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.
Critical Impact
Affected Products
- SOGo: see the vendor advisory for the exact affected versions
Discovery Timeline
- 2026-11-12: CVE-2026-127131 published to the National Vulnerability Database by disclosure@vulncheck.com
- 2026-11-12: last updated in the NVD database
Technical Details for CVE-2026-127131
Vulnerability Analysis
CVE-2026-127131 is a Security Vulnerability weakness (CWE-307) in SOGo. Based on its CVSS vector, the flaw can be reached over the network, needs no login, and needs no user interaction.
With a CVSS base score of 9.1, apply the vendor fix and confirm exposure on internet facing and business critical assets first.
Root Cause
The vendor description states: 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.
Attack Vector
Based on the CVSS vector, the flaw can be reached over the network, needs no login, and needs no user interaction. Attack complexity is high complexity.
No exploitation in the wild is confirmed by CISA at the time of the last update. Check the references below for any vendor or researcher proof of concept.
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Detection Methods for CVE-2026-127131
Detection Strategies
- Inventory every instance of SOGo and compare the running version with the affected range above.
- Check external attack surface scans for internet facing instances of the component.
- Run an authenticated vulnerability scan once your scanner ships a check for this CVE.
Monitoring Recommendations
- Forward SOGo application, access and audit logs to your SIEM for retrospective hunting.
- Alert on new processes, configuration changes or outbound connections from the affected service.
- Track the vendor advisory and the CISA KEV catalog for changes in exploitation status.
How to Mitigate CVE-2026-127131
Immediate Actions Required
- Apply the fixed version of SOGo named in the vendor advisory.
- Prioritize internet facing and business critical instances first.
- Rescan after the change to confirm the exposure is closed.
Patch Information
Use the fixed version listed in the vendor advisory for SOGo.
Workarounds
- If patching must wait, restrict network access to the affected service and place it behind authentication or a web application firewall rule.
CWE References
Technical References
This entry is built directly from NVD, CISA KEV and EPSS data. Verify fixed versions in the vendor advisory before you deploy.
Frequently asked questions
Related CVEs
OpenEMR from 7.0.1 before 8.4.0 contains a flaw in src/Common/Auth/OneTimeAuth.php that ignores the enforce_onetime_use and max_access_count flags, never revokes consumed service_auth tokens, and checks login_pin without rate limiting or strict comparison. Attackers holding a captured token can replay it or brute-force the PIN to open patient-portal sessions exposing PHI.
Databasus 3.7.0 through 3.61.0 contains an authentication bypass vulnerability that allows unauthenticated attackers to brute-force password reset codes via POST /api/v1/users/reset-password. Attackers can request a six-digit code for a known email, then guess it without rate limiting, lockout, or invalidation to take over accounts, including administrators.
Shenzhen Tenda W30E V2 firmware versions up to and including V16.01.0.19(5037) do not enforce rate limiting or account lockout mechanisms on authentication endpoints. This allows attackers to perform unrestricted brute-force attempts against administrative credentials.
SOGo before 5.12.13 contains an improper restriction of excessive authentication attempts vulnerability that allows unauthenticated attackers to reset account passwords by repeatedly guessing secret-question answers via the passwordRecoveryCheck endpoint without lockout or rate limiting. Attackers can submit unlimited candidate answers to obtain a valid recovery JWT, then use it to change the account password without the old credential and log in via the connect endpoint, achieving full account takeover on accounts without TOTP enabled.
Tandoor Recipes is an application for managing recipes, planning meals, and building shopping lists. In versions prior to 2.6.0, Tandoor Recipes configures Django REST Framework with BasicAuthentication as one of the default authentication backends. The AllAuth rate limiting configuration (ACCOUNT_RATE_LIMITS: login: 5/m/ip) only applies to the HTML-based login endpoint at /accounts/login/. Any API endpoint that accepts authenticated requests can be targeted via Authorization: Basic headers with zero rate limiting, zero account lockout, and unlimited attempts. An attacker can perform high-speed password guessing against any known username. Version 2.6.0 patches the issue.
Outline is a service that allows for collaborative documentation. Outline implements an Email OTP login flow for users not associated with an Identity Provider. Starting in version 0.86.0 and prior to version 1.6.0, Outline does not invalidate OTP codes based on amount or frequency of invalid submissions, rather it relies on the rate limiter to restrict attempts. Consequently, identified bypasses in the rate limiter permit unrestricted OTP code submissions within the codes lifetime. This allows attackers to perform brute force attacks which enable account takeover. Version 1.6.0 fixes the issue.
Earn your free CTEM certification.
Learn to scope, prioritize, validate and mobilize fixes for CVEs like CVE-2026-127131 with a free CTEM certification.
Beginner / Practitioner / Program Leader
Explore certifications