CVE-2026-4965

High

Published: 27 March 2026

Published

27 March 2026

Modified

30 March 2026

KEV Added

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Patch

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CVSS Score 7.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

EPSS Score 0.0002 6.6th percentile

Risk Priority 15 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2026-4965 is a high-severity Code Injection (CWE-94) vulnerability. Its CVSS base score is 7.3 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 6.6th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

This vulnerability is AI-related — categorised as Other AI Platforms.

The strongest mitigations our analysis identified are NIST 800-53 SI-10 (Information Input Validation) and SI-2 (Flaw Remediation).

Threat & Defense at a Glance

What attackers do: exploitation maps to Exploit Public-Facing Application (T1190) and 1 other technique. What defenders deploy: see the NIST 800-53 controls recommended below.

Threat & Defense Details

Mitigating Controls (NIST 800-53 r5)AI

SI-2 Flaw Remediation good match

prevent

Directly requires timely remediation of the specific code injection flaw in letta 0.16.4's resolve_type function via patches or compensating controls.

SI-10 Information Input Validation good match

prevent

Mandates validation of inputs to the ast_parsers.py function to neutralize malicious directives before dynamic code evaluation.

SI-16 Memory Protection partial match

prevent

Implements memory protections like non-executable regions to mitigate arbitrary code execution even if injection succeeds.

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access

Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.

attack.mitre.org →

T1059.006 Python Execution

Adversaries may abuse Python commands and scripts for execution.

attack.mitre.org →

Why these techniques?

Remote unauthenticated code injection (CWE-94/95) in Python dynamic evaluation directly enables T1190 (Exploit Public-Facing Application) for initial access and T1059.006 (Python) for arbitrary code execution.

Confidence: HIGH · MITRE ATT&CK Enterprise v18.1

NVD Description

A vulnerability was detected in letta-ai letta 0.16.4. This issue affects the function resolve_type of the file letta/functions/ast_parsers.py of the component Incomplete Fix CVE-2025-6101. Performing a manipulation results in improper neutralization of directives in dynamically evaluated code. The attack can…

be initiated remotely. The exploit is now public and may be used. The vendor was contacted early about this disclosure but did not respond in any way.

Deeper analysisAI

CVE-2026-4965 is a code injection vulnerability stemming from an incomplete fix for CVE-2025-6101 in the letta-ai letta framework version 0.16.4. It affects the resolve_type function within the file letta/functions/ast_parsers.py, where improper neutralization of directives in dynamically evaluated code (classified under CWE-94 and CWE-95) allows malicious input to be processed unsafely. The issue carries a CVSS v3.1 base score of 7.3 (AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L), indicating high severity due to its network accessibility and lack of prerequisites.

Remote attackers can exploit this vulnerability without authentication or user interaction by manipulating inputs to the affected function, potentially leading to arbitrary code execution or directive injection during dynamic code evaluation. Successful exploitation grants low-level impacts on confidentiality, integrity, and availability, enabling data leakage, modification of application state, or denial of service within the letta framework's parsing context.

Advisories from VulDB (ctiid.353842, id.353842, submit.777654) document the issue, with a public exploit available via a GitHub Gist (https://gist.github.com/YLChen-007/fc09bc447a73bba526c1642d9ce73ca5). No patches or vendor responses are reported, as the letta-ai team was contacted early but did not reply; security practitioners should avoid version 0.16.4 and monitor for updates.

The exploit's public availability increases the risk of active exploitation, particularly in environments using letta-ai for AI-related dynamic code processing.