Out-of-bounds Read in Ocaml

CVE-2026-28364

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.

Published · last modified .

CVSS v3 metric

CVSS v3 base score 7.9 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N.

EPSS exploit prediction

EPSS: 0.003 (22.9th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 23rd percentile — 22.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-28364: held from 0.002 to 0.003.

EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.001

Affected products

  • Ocaml — versions 0, 5.0.0

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-28364?
CVE-2026-28364 is a high-severity vulnerability in Ocaml, classified under Buffer Over-read. CVSS score: 7.9/10. Published 2026-02-27.
How severe is CVE-2026-28364?
High severity. CVSS v3 base score is 7.9 out of 10.