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TI-2026-76668 Aliases CVE-2026-77938

Letta tool sandbox exposes server secrets to tool users

Priority MEDIUM 64CWE-526Published · Updated

Key facts

Attack vector
Network
Privileges required
Low
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
—
Confidentiality · integrity · availability
High · None · None
Fix status
No fix listed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA.

Summary

Letta through 0.16.8 lets users who run tools read server secrets, because LocalSandbox subprocesses inherit the full server environment. A user with low privileges can run code through POST /v1/tools/run or custom tools to read database credentials and provider API keys, then access cross-tenant database data. The weakness is classified as CWE-526, cleartext storage of sensitive information in an environment variable. A proof-of-concept exploit is linked in the references.

Written with Claude Haiku 5.5 from the sources below · 2026-10-28

Description from the CNA

Letta through 0.16.8 contains an information disclosure vulnerability that allows users running tools to read server secrets because LocalSandbox subprocesses inherit the full server environment. Attackers can run code via POST /v1/tools/run or custom tools to read LETTA_PG_URI, POSTGRES_PASSWORD, and provider API keys, then access cross-tenant database data.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00416 36th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by the CNA
Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
letta-ailettaup to 0.16.8—No fix listedCNA
  • letta Vendorletta-ai Affected up to 0.16.8 Fixed in — No fix listed CNA

Remediation

The sources list no fixed version for letta.

Written with Claude Haiku 5.5 from the sources below · 2026-10-28

Timeline

  1. 2026-10-20 Threatist record created from CVE-2026-77938
  2. 2026-10-20 CISA SSVC decision points changed

References

Exploit 1

Other 1

  • TI-2026-76666 Insecure default configuration in Letta exposes API and PostgreSQL CVSS 4.0CRITICAL 9.3
  • TI-2026-76667 Letta lets API callers impersonate other users via user_id header CVSS 4.0HIGH 8.6
  • TI-2026-15517 letta-ai LettaBot API Status Route server.ts missing authentication CVSS 4.0MEDIUM 6.9
  • TI-2025-05511 letta-ai letta interface.py function_message eval injection CVSS 4.0MEDIUM 5.1

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences