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CVE-2026-28364

30
FAUCET Score

CVE-2026-28364 describes a buffer over-read vulnerability in OCaml's Marshal deserialization, affecting versions before 4.14.3 and 5.x before 5.4.1. This flaw, stemming from missing bounds validation in the readblock() function, allows for unbounded memcpy() operations using attacker-controlled lengths. With a CVSS score of 7.8 (HIGH), successful exploitation can lead to remote code execution, impacting confidentiality, integrity, and availability. While there is no known active exploitation or public exploit code (Metasploit, Nuclei, ExploitDB), the vulnerability has garnered significant community discussion, indicating awareness among security researchers.

Impacted Technologies

VendorProductVersion(s)CPE
< 4.14.3CPE matchmatch criteria
cpe:2.3:a:ocaml:ocaml:*:*:*:*:*:*:*:*
>= 5.0.0, < 5.4.1CPE matchmatch criteria
cpe:2.3:a:ocaml:ocaml:*:*:*:*:*:*:*:*
>= 0, < 4.14.3CPE match
cpe:2.3:a:ocaml:ocaml:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.9HIGH

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

Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
HIGH
Integrity Impact
LOW
Availability Impact
NONE
Exploitability Score
2.5
Impact Score
4.7
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.21%
Probability of exploitation in next 30 days
EPSS Percentile
11.4%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0021 is in the 39th percentile among its peer group of 17,070 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.2 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (5)

microsoftpatch availablevia msrc
Product: azl3 ocaml 5.1.1-1 on Azure Linux 3.0Fixed in: 5.1.1-2
microsoftpatch availablevia msrc
Product: cbl2 ocaml 4.13.1-2 on CBL Mariner 2.0Fixed in: 4.13.1-3
microsoftpatch availablevia msrc
Product: 20930-17084Fixed in: 5.1.1-2
microsoftpatch availablevia msrc
Product: 21039-17086Fixed in: 4.13.1-3
github_advisoryvendor investigatingvia nvd_reference
View patch

Vendor Advisories (1)

microsoft2026-Feb/CVE-2026-28364Important

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.

Feb 10, 2026

References

access.redhat.com / security/cve/CVE-2026-28364
bugzilla.redhat.com / show_bug.cgi
security.access.redhat.com / data/csaf/v2/vex/2026/cve-2026-28364.json
github.com / ocaml/security-advisories/blob/generated-osv/2026/OSEC-2026-01.json
Vendor Advisory
osv.dev / vulnerability/OSEC-2026-01
Third Party Advisory