Catalog analysis: CISA added this entry on September 02, 2026. The entry reflects catalog information retrieved on September 02, 2026, not a snapshot archived on the inclusion date. This site’s publication date is shown separately. Check current vendor guidance before acting.
What the vulnerability is
CVE-2026-59822 is an improper authentication vulnerability (CWE-287, CWE-306) affecting BerriAI LiteLLM. The flaw resides in the MCP Streamable HTTP endpoint. If exploited, an unauthenticated attacker could establish an authenticated MCP session by providing an arbitrary Bearer token, bypassing intended security controls.
Exposure and applicability
This vulnerability applies to deployments of BerriAI LiteLLM utilizing the MCP Streamable HTTP endpoint. The risk is highest for instances with direct internet exposure, as the lack of authentication requirements for session establishment provides a primary entry path for external actors. Organizations should identify all active LiteLLM instances and determine if the affected endpoint is reachable from untrusted networks.
Remediation priorities
Because this vulnerability has been added to CISA’s Known Exploited Vulnerabilities (KEV) catalog as of September 2, 2026, remediation should be prioritized.
Our analysis suggests the following priority sequence:
1. Immediate Mitigation: Apply vendor-supplied mitigations according to BerriAI instructions. For federal agencies, CISA has established a compliance deadline of September 16, 2026.
2. Exposure Reduction: Evaluate and restrict internet-facing access to the MCP Streamable HTTP endpoint. Implementing network-level access controls (such as IP allowlisting or VPN requirements) can reduce the likelihood of exploitation while patching is underway.
3. Service Evaluation: In scenarios where mitigations cannot be applied, organizations should evaluate whether to discontinue use of the product to eliminate the exposure entirely.
How to validate remediation
Verification must go beyond checking software version numbers. To ensure that the vulnerability has been mitigated and the risk reduced, defenders should perform a functional test of the MCP Streamable HTTP endpoint’s authentication mechanism.
Validation is achieved when an attempt to establish a session using an arbitrary or invalid Bearer token is explicitly rejected by the system. A successful mitigation is confirmed only when the endpoint no longer accepts unauthorized tokens to grant authenticated session access.
Limits and open questions
While vendor mitigations address the authentication flaw, residual risk remains if the underlying network architecture allows broad access to sensitive endpoints. It is currently unknown whether this vulnerability has been utilized in ransomware campaigns. Additionally, while CISA provides a deadline for federal agencies, non-federal organizations must determine their own remediation timelines based on their specific risk profile and asset exposure.
Source and editorial note
CVE-2026-59822: BerriAI LiteLLM Improper Authentication Vulnerability · Source date: September 02, 2026 · Retrieved September 02, 2026.
Material facts are tied to the cited primary source. Recommendations are independent defensive analysis unless attributed to the source. Confirm consequential decisions against current authoritative guidance.
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