PatchSiren

PatchSiren cyber security CVE debrief

CVE-2026-45675 open-webui CVE debrief

Open WebUI versions prior to 0.9.0 contain a Time-of-Check-Time-of-Use (TOCTOU) race condition in LDAP and OAuth authentication flows that could allow unauthorized elevation to administrator privileges. The vulnerability exists because while the regular signup handler was patched to prevent this race condition with a default-role-first insertion pattern, the LDAP and OAuth code paths were never updated with the same fix. An attacker with network access could potentially exploit this timing window during first-user creation to gain administrative control of the platform. The CVSS 3.1 score of 8.1 (High) reflects network attack vector, high attack complexity, no required privileges or user interaction, and high impacts to confidentiality, integrity, and availability. The issue was disclosed on May 15, 2026 and modified on May 19, 2026. No known exploitation in ransomware campaigns has been reported.

Vendor
open-webui
Product
Unknown
CVSS
HIGH 8.1
CISA KEV
Not listed in stored evidence
Original CVE published
2026-05-15
Original CVE updated
2026-05-19
Advisory published
2026-05-15
Advisory updated
2026-05-19

Who should care

Organizations running Open WebUI versions prior to 0.9.0 with LDAP or OAuth authentication enabled, particularly those relying on first-user admin assignment for initial deployment configuration. Security teams responsible for self-hosted AI platform infrastructure and identity management administrators should prioritize this patch.

Technical summary

A Time-of-Check-Time-of-Use (TOCTOU) vulnerability exists in Open WebUI's LDAP and OAuth authentication handlers prior to version 0.9.0. The regular signup handler (signup_handler in auths.py) was previously patched to prevent a race condition during first-user admin role assignment by inserting with default role first, but this fix was not propagated to the LDAP and OAuth code paths. This inconsistency creates a window where concurrent authentication requests could result in unauthorized administrative privilege assignment. The vulnerability requires network access and is rated CVSS 3.1 8.1 (High). The fix in version 0.9.0 applies the same defensive pattern to all authentication flows.

Defensive priority

HIGH

Recommended defensive actions

  • Upgrade Open WebUI to version 0.9.0 or later to eliminate the TOCTOU race condition in authentication flows.
  • If immediate patching is not possible, review and monitor first-user creation events in LDAP and OAuth authentication logs for anomalous timing patterns or duplicate account creation attempts.
  • Verify that any existing Open WebUI deployments using LDAP or OAuth authentication have not experienced unauthorized administrative account creation prior to patching.
  • Consider implementing additional access controls or rate limiting on authentication endpoints to reduce the attack surface for race condition exploitation.

Evidence notes

The vulnerability description and fix details are sourced from NVD and GitHub Security Advisory GHSA-h3ww-q6xx-w7x3. The patch commit 96a0b3239b1aadb23fc359bf10849c9ba12fd6ec addresses the TOCTOU race by applying the same default-role-first pattern to LDAP and OAuth flows that was previously implemented for regular signup. CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization) and CWE-269 (Improper Privilege Management) are identified as relevant weakness classifications.

Official resources

2026-05-15