CVE-2026-55774 openbao CVE debrief

Who should care

OpenBao administrators and users with access to sys/leases/revoke/:lease_id, especially those managing deployments with multiple namespaces, should verify access controls and assess deployments for namespace ACL isolation bypass vulnerability. They should also review and update OpenBao configurations to ensure proper namespace isolation and verify remediation by upgrading to OpenBao version 2.5.5 or later.

Why it matters

CVE-2026-55774 allows OpenBao users with access to sys/leases/revoke/:lease_id in one namespace to revoke leases in another namespace, bypassing namespace ACL isolation. This issue is fixed in version 2.5.5.

• Verify access controls for sys/leases/revoke/:lease_id to prevent unauthorized lease revocation
• Assess OpenBao deployments for namespace ACL isolation bypass vulnerability
• Review and update OpenBao configurations to ensure proper namespace isolation

Technical summary

OpenBao users with access to sys/leases/revoke/:lease_id in one namespace could revoke leases in another namespace if the foreign lease_id was known, bypassing namespace ACL isolation. This issue is fixed in version 2.5.5. The affected lease lookup routing in vault/expiration.go allowed FetchLeaseInfo and loadEntry to resolve cached or stored lease data outside the request namespace, allowing a tenant that intentionally disclosed a lease identifier to have the lease and its underlying credential revoked by another tenant. The vulnerability was addressed by fixing the lease lookup routing to enforce namespace isolation properly.

Defensive priority

Assess exposure and verify remediation for OpenBao deployments, especially those with multiple namespaces.

Recommended defensive actions

• Assess OpenBao deployments for namespace ACL isolation bypass vulnerability
• Verify remediation by upgrading to OpenBao version 2.5.5 or later
• Review access controls for sys/leases/revoke/:lease_id
• Verify access controls for sys/leases/revoke/:lease_id to prevent unauthorized lease revocation
• Assess exposure and verify remediation for OpenBao deployments, especially those with multiple namespaces.
• Review and update OpenBao configurations to ensure proper namespace isolation
• Track exceptions, retest remediated assets, and close the item only after evidence is documented.

Evidence notes

The CVE record and NVD entry provide details on the vulnerability and its fix. OpenBao's security advisory provides additional context. The vulnerability was introduced due to a flawed lease lookup routing in vault/expiration.go, allowing FetchLeaseInfo and loadEntry to resolve cached or stored lease data outside the request namespace. This issue could be exploited by a tenant that intentionally discloses a lease identifier to have the lease and its underlying credential revoked by another tenant.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.