CVE-2026-28364

High

Published: 27 February 2026

Published

27 February 2026

Modified

06 March 2026

KEV Added

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Patch

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CVSS Score 7.9 CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N

EPSS Score 0.0005 15.7th percentile

Risk Priority 16 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2026-28364 is a high-severity Buffer Over-read (CWE-126) vulnerability in Ocaml Ocaml. Its CVSS base score is 7.9 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 15.7th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

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 Exploitation for Privilege Escalation (T1068). 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

Applying vendor patches to OCaml versions 4.14.3 or 5.4.1 directly remediates the buffer over-read flaw in Marshal deserialization.

SI-10 Information Input Validation good match

prevent

Validating bounds and structure of input data prior to Marshal deserialization prevents processing of attacker-controlled lengths leading to unbounded memcpy.

SI-16 Memory Protection partial match

prevent

Memory protection mechanisms like ASLR and DEP mitigate exploitation of the buffer over-read for remote code execution.

MITRE ATT&CK Enterprise TechniquesAI

T1068 Exploitation for Privilege Escalation Privilege Escalation

Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.

attack.mitre.org →

Why these techniques?

Buffer over-read in OCaml Marshal deserialization (unbounded memcpy from attacker-controlled lengths) enables local unauthenticated attackers to achieve arbitrary code execution, directly facilitating T1068 Exploitation for Privilege Escalation (AV:L/PR:N to code exec with scope change).

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

NVD Description

In OCaml before 4.14.3 and 5.x before 5.4.1, a buffer over-read in Marshal deserialization (runtime/intern.c) enables remote code execution through a multi-phase attack chain. The vulnerability stems from missing bounds validation in the readblock() function, which performs unbounded memcpy() operations…

using attacker-controlled lengths from crafted Marshal data.

Deeper analysisAI

CVE-2026-28364 is a buffer over-read vulnerability (CWE-126) in the Marshal deserialization functionality of OCaml, located in the runtime/intern.c file's readblock() function. It affects OCaml versions before 4.14.3 and 5.x versions before 5.4.1. The flaw results from missing bounds validation, enabling unbounded memcpy() operations controlled by lengths from attacker-crafted Marshal data.

A local attacker (AV:L) with no privileges (PR:N), low attack complexity (AC:L), and no user interaction (UI:N) can exploit this vulnerability through a multi-phase attack chain. Successful exploitation leads to remote code execution, with a CVSS v3.1 base score of 7.9 (S:C/C:H/I:L/A:N), providing high confidentiality impact, low integrity impact, no availability impact, and changed scope.

Advisories detail mitigations in the referenced security notices, including patches in OCaml 4.14.3 and 5.4.1. See https://github.com/ocaml/security-advisories/blob/generated-osv/2026/OSEC-2026-01.json and https://osv.dev/vulnerability/OSEC-2026-01 for full details.