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CriticalVulnerabilityCVE-2026-77936updated 25 Oct 2026, 15:20 UTC

Letta server accepts requests with no login and exposes its database

The Letta server ships with a setup file that turns off its password check, so anyone who can reach it over the network can run code on it and read or change its database. A database port is also open with a known default password.

Official, 2 sources
SeverityCriticalCVSS 9.3 of 10
Being exploited?UnclearNo reports either way yet
Fix available?UnclearNo fixed version published in the sources yet
How sure is this?Official, 2 sourcesBacked by an official source

How the attack works simplified

  1. 1Remote attackerReaches the server over the network
  2. 2Letta APINo login check on routes
  3. 3Run Python codeVia /v1/tools/run endpoint
  4. 4PostgreSQL accessDefault superuser credentials exposed
  5. ResultAttacker controls the server

What happened

Letta through 0.16.8 ships a compose.yaml that leaves LETTA_SERVER_SECURE unset, so the password middleware is never added and all API routes are unauthenticated; it also exposes a superuser PostgreSQL port with default credentials.

Why it is dangerous: Remote attackers can execute arbitrary Python via POST /v1/tools/run, manage admin users via /v1/admin, or run OS commands via COPY PROGRAM, giving them full control of the server and its data.

Are you affected?

You are affected if you run Letta through 0.16.8 using its provided compose.yaml without setting LETTA_SERVER_SECURE, especially if the server or its PostgreSQL port is reachable from a network.

Letta through 0.16.8 (compose.yaml configuration)

What to do

  1. Set LETTA_SERVER_SECURE to enable the password check in your compose.yaml
  2. Change the default PostgreSQL superuser credentials and stop exposing the database port
  3. Block public network access to the Letta server and database until fixed
  4. Check the GitHub advisory GHSA-g524-hhf9-5x95 for an updated version

Timeline

  1. 20 Oct 2026, 01:17 UTC
    Publicly disclosed
  2. 20 Oct 2026, 01:17 UTC
    Reported by NVD · NVD
  3. 25 Oct 2026, 15:20 UTC
    GitHub Advisory reported on it · GitHub Advisory

Sources 2 reports, oldest first

Official vendor, government CERT or advisory database

Technical details

ID
CVE-2026-77936 · GHSA-g524-hhf9-5x95
CVSS
9.3 / 10
EPSS
0.6% chance of exploitation within 30 days
Disclosed
20 Oct 2026, 01:17 UTC
On Zero Radar
before the radar started
Last change
25 Oct 2026, 15:20 UTC

The plain-language parts and the attack diagram were written by an AI model (anthropic/claude-haiku-5.5) from the sources above. Facts like versions, exploitation and dates come from the sources themselves. How Zero Radar works

Letta server accepts requests with no login and exposes its database · Zero Radar