dbcve.org
OcamlApplication

CVE-2018-9838

CRITICAL · 9.8 CVSS v3.0 Published 2018-04-06
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
The caml_ba_deserialize function in byterun/bigarray.c in the standard library in OCaml 4.06.0 has an integer overflow which, in situations where marshalled data is accepted from an untrusted source, allows remote attackers to cause a denial of service (memory corruption) or possibly execute arbitrary code via a crafted object.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Integer overflow vulnerability in OCaml 4.06.0's caml_ba_deserialize function within byterun/bigarray.c allows memory corruption or arbitrary code execution when deserializing untrusted marshalled data.

MitigationUpgrade to a patched version of OCaml; if immediate upgrade is not feasible, avoid accepting marshalled data from untrusted sources or implement strict input validation on the marshalled data before deserialization.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
OcamlApplication
Affected:= 4.06.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Verify OCaml is installed
    Run `ocaml --version` or check for ocaml binaries in standard paths like /usr/bin/ocaml
    Affected if OCaml is not installed - not affected
  2. Confirm the exact OCaml version
    Examine the version output from `ocaml --version`. This CVE affects only version 4.06.0 exactly.
    Affected if Version is 4.06.0 - potentially affected; versions lower or higher than 4.06.0 are not affected by this specific CVE
  3. Identify Bigarray usage in your application
    Search source code for references to `Bigarray` module and its deserialization functions (e.g., `caml_ba_deserialize`, `Marshal.from_*` with Bigarray arrays, or use of the `bigarray` library)
    Affected if Your code does not use Bigarray deserialization - not affected
  4. Determine if marshalled data is received from untrusted sources
    Audit input handling code to check if the application accepts marshalled data from network connections, user uploads, files from untrusted locations, or other external untrusted sources
    Affected if Marshalled data from untrusted sources is deserialized using Bigarray - affected; trusted/internal only data - not affected

You are affected only if running exactly OCaml 4.06.0 AND your application deserializes Bigarray objects from untrusted marshalled data sources.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade to a patched version of OCaml; if immediate upgrade is not feasible, avoid accepting marshalled data from untrusted sources or implement strict input validation on the marshalled data before deserialization.

Recommended fix High confidence

OCaml 4.06.1 or later (preferably latest stable 4.x release)

  1. 1. Identify all systems running OCaml 4.06.0 that accept marshalled data from untrusted sources
  2. 2. Upgrade OCaml to version 4.06.1 or later (recommended: latest stable 4.x release)
  3. 3. For package-based deployments, update via opam switch upgrade or system package manager
  4. 4. Rebuild any dependent packages after upgrading the OCaml compiler
  5. 5. Test application functionality to ensure compatibility with the new OCaml version
  6. 6. If immediate upgrade is not feasible, audit code to avoid using input_value or similar deserialization functions on untrusted data, and consider implementing input validation layers
Caveat Minimal; 4.06.1 is a patch release focused on bug fixes and security patches with high backward compatibility

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Ocaml Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing6.0 h
  • Review / QA3.0 h
18.0 hours of engineering $3,120
Get help mitigating

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,992.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2018-9838 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2018-9838 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data