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.
References (2)
Core 2
Core References
Third Party Advisory
https://github.com/ocaml/security-advisories/blob/generated-osv/2026/OSEC-2026-01.json
Various Sources
https://osv.dev/vulnerability/OSEC-2026-01
Scores
CVSS v3
7.9
EPSS
0.0018
EPSS Percentile
7.9%
Attack Vector
LOCAL
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N
CISA SSVC
Vulnrichment
Exploitation
none
Automatable
no
Technical Impact
partial
Details
CWE
CWE-126
Status
published
Products (1)
ocaml/ocaml
< 4.14.3
Published
Feb 27, 2026
Tracked Since
Feb 27, 2026