CVE-2026-31240: mem0 Authentication Bypass Vulnerability

CVE-2026-31240 Overview

CVE-2026-31240 affects the mem0 1.0.0 server, which exposes its memory management API without authentication or authorization controls. The PUT /memories/{memory_id} endpoint accepts requests from any unauthenticated network client. A remote attacker can modify, overwrite, or delete arbitrary memory records stored by the application. The flaw is classified under CWE-306: Missing Authentication for Critical Function. The mem0 project provides memory persistence for AI agents and large language model (LLM) applications, making the integrity of stored memories security-relevant for downstream AI workflows.

Critical Impact

Unauthenticated remote attackers can tamper with or destroy memory records used by AI agents, causing data integrity loss and potential corruption of LLM-driven decisions.

Affected Products

• mem0 server version 1.0.0
• mem0 memory management REST API endpoints
• Applications and AI agents depending on mem0 for persistent memory

Discovery Timeline

• 2026-05-12 - CVE-2026-31240 published to NVD
• 2026-05-14 - Last updated in NVD database

Technical Details for CVE-2026-31240

Vulnerability Analysis

The mem0 1.0.0 server implements a REST API for managing memory records used by AI agents. The server does not enforce authentication on its memory management endpoints. The PUT /memories/{memory_id} endpoint accepts update requests without verifying the requester's identity or permissions. Any client able to reach the service over the network can submit a request and modify the targeted memory record.

Because mem0 stores contextual memory consumed by LLM applications, integrity of these records affects downstream model behavior. An attacker can overwrite memory content used for retrieval-augmented generation (RAG) or agent state. The result is poisoned context, falsified history, or destroyed records. Confidentiality and availability are not directly impacted, but data integrity is compromised. The vulnerability requires only network reachability to the mem0 service.

Root Cause

The root cause is missing authentication for a critical function [CWE-306]. The mem0 server does not require API keys, bearer tokens, session cookies, or any other credential before processing state-changing requests. Authorization checks tying a memory record to an owning user or tenant are also absent. Any request reaching the endpoint is treated as authorized.

Attack Vector

The attack is performed remotely over the network. An attacker who can reach the mem0 HTTP listener sends a crafted PUT request to /memories/{memory_id} with arbitrary content in the request body. No prior authentication step is required and no user interaction is needed. The same exposure applies to other memory management endpoints that lack authentication, including delete operations. Deployments that expose mem0 directly to the internet, or to untrusted internal networks, are reachable by any attacker on those segments. The vulnerability is described in prose only; refer to the mem0 project repository for endpoint definitions.

Detection Methods for CVE-2026-31240

Indicators of Compromise

• Unauthenticated HTTP PUT or DELETE requests to /memories/{memory_id} paths in mem0 access logs
• Memory records modified outside the patterns of legitimate application clients, including unexpected timestamps or source IP addresses
• Sudden drops in memory record counts or unexplained content changes reported by downstream AI agents

Detection Strategies

• Enable verbose HTTP access logging on the mem0 server and forward logs to a centralized analytics platform for review
• Baseline normal client IP ranges, user agents, and request volumes against the memory API, then alert on deviations
• Apply integrity monitoring to memory record content, flagging unexpected mutations or deletions on records that should be append-only

Monitoring Recommendations

• Monitor network traffic to the mem0 service port for traffic originating outside the approved application tier
• Track API request rates per source IP and alert when a single source issues high volumes of PUT or DELETE requests
• Correlate mem0 modification events with upstream application authentication events to detect modifications lacking a corresponding user session

How to Mitigate CVE-2026-31240

Immediate Actions Required

• Remove mem0 from any network segment reachable by untrusted clients and bind the service to a loopback or private interface
• Place an authenticating reverse proxy in front of the mem0 API to enforce API key or OAuth checks before requests reach the backend
• Audit existing memory records for unauthorized modification and restore from trusted backups where tampering is suspected

Patch Information

No vendor patch is listed in the NVD entry at the time of publication. Track the mem0 GitHub repository for fixes that introduce authentication and per-record authorization on the memory management endpoints. Upgrade to a fixed release as soon as one becomes available.

Workarounds

• Front the mem0 server with a reverse proxy such as NGINX or Envoy that requires an API key or mutual TLS for every request
• Restrict inbound network access to the mem0 port using host firewall rules or cloud security groups limited to known application servers
• Run mem0 inside an isolated network namespace or service mesh that enforces mutual TLS between the application and mem0

# Example NGINX reverse proxy snippet enforcing an API key before reaching mem0
server {
    listen 443 ssl;
    server_name mem0.internal.example.com;

    location /memories/ {
        if ($http_x_api_key != "REPLACE_WITH_STRONG_SECRET") {
            return 401;
        }
        proxy_pass http://127.0.0.1:8000;
        proxy_set_header Host $host;
    }
}