CVE-2026-33758
CRITICALCVSS Vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/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
Lifecycle Timeline
3Tags
Description
### Impact OpenBao installations that have an OIDC/JWT authentication method enabled and a role with `callback_mode=direct` configured are vulnerable to XSS via the `error_description` parameter on the page for a failed authentication. This allows an attacker access to the token used in the Web UI by a victim. ### Patches The `error_description` parameter has been replaced with a static error message in v2.5.2 ### Workarounds The vulnerability can be mitigated by removing any roles with `callback_mode` set to `direct`.
Analysis
Cross-site scripting in OpenBao's OIDC/JWT authentication method allows theft of Web UI session tokens when roles are configured with callback_mode=direct. Attackers exploit the unsanitized error_description parameter on failed authentication pages to inject malicious scripts that execute in victims' browsers, granting access to authentication tokens. …
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Remediation
Within 24 hours: Inventory all OpenBao deployments and identify instances running versions prior to v2.5.2 with OIDC/JWT authentication enabled and callback_mode=direct configured. Within 7 days: Apply vendor patch by upgrading to OpenBao v2.5.2 or later on all affected systems. …
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