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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.21%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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.
- CVSS 3.1
- 7.8 HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 0.21% probability · 11th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-126, CWE-125
- Affected
- ocaml/ocaml
- Source
- cve@mitre.org
References
- https://github.com/ocaml/security-advisories/blob/generated-osv/2026/OSEC-2026-01.jsonVendor Advisory
- https://osv.dev/vulnerability/OSEC-2026-01Third Party Advisory
- https://access.redhat.com/security/cve/CVE-2026-28364
- https://bugzilla.redhat.com/show_bug.cgi?id=2443348
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-28364.json
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.