What is CVE-2026-77936?

CVE-2026-77936 is a critical-severity vulnerability in Letta-Ai Letta, classified under Initialization of a Resource with an Insecure Default. CVSS score: 9.8/10. Published 2026-10-20.

How severe is CVE-2026-77936?

Critical severity. CVSS v3 base score is 9.8 out of 10.

RCE in Letta-Ai Letta

CVE-2026-77936

Letta through 0.16.8 ships a compose.yaml that does not enable LETTA_SERVER_SECURE, so the password middleware is never added and all API routes are unauthenticated, and it exposes a superuser PostgreSQL port with default credentials. Remote attackers can execute arbitrary Python via POST /v1/tools/run, manage /v1/admin users, or run OS commands via COPY PROGRAM.

Published 2026-10-20.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Letta-Ai Letta

Weakness classification (CWE)

CWE-1188 — Initialization of a Resource with an Insecure Default

References

github.com/letta-ai/letta/blob/1131535716e8a31c9a437f8695e25ac98f203a24/compose… (technical-description)
github.com/letta-ai/letta/blob/1131535716e8a31c9a437f8695e25ac98f203a24/letta/s… (technical-description)
Lasso.security Advisory (technical-description, exploit)
VulnCheck Advisory: Letta through 0.16.8 Insecure Default Configuration Unauthenticated API and PostgreSQL Access (third-party-advisory)

Frequently asked questions

What is CVE-2026-77936?: CVE-2026-77936 is a critical-severity vulnerability in Letta-Ai Letta, classified under Initialization of a Resource with an Insecure Default. CVSS score: 9.8/10. Published 2026-10-20.
How severe is CVE-2026-77936?: Critical severity. CVSS v3 base score is 9.8 out of 10.