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Vulnerability · Published Feb 27, 2026 · Assigned by mitre

CVE-2026-28364

High 7.9

In plain English

A high-severity out-of-bounds read in OCaml from OCaml. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 15% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code. Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.9High
Exploit odds (30 days)0.2%top 84.7% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack tooling1Public PoC

Official 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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12ocamlno fix listedDEBIAN-CVE-2026-28364
Debian:13ocamlno fix listedDEBIAN-CVE-2026-28364
Debian:14ocaml5.4.1-1DEBIAN-CVE-2026-28364
Ubuntu:22.04:LTSocamlno fix listedUBUNTU-CVE-2026-28364
Ubuntu:24.04:LTSocamlno fix listedUBUNTU-CVE-2026-28364
Ubuntu:25.10ocamlno fix listedUBUNTU-CVE-2026-28364
Ubuntu:26.04:LTSocamlno fix listedUBUNTU-CVE-2026-28364
Ubuntu:26.10ocamlno fix listedUBUNTU-CVE-2026-28364

Affected products (as reported)

VendorProductVersions
OCaml OCaml 0 – before 4.14.35.0.0 – before 5.4.1

Weakness: CWE-126, CWE-125 · Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N

References