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OSEC-2016-01

CriticalCVSS 9.1 / 10
Published Apr 29, 2016·Last modified Feb 17, 2026
Affected Components(0)

No affected components available

Description

Bug description

OCaml versions 4.02.3 and earlier have a runtime bug that, on 64-bit platforms, causes sizes arguments to an internal memmove call to be sign-extended from 32 to 64-bits before being passed to the memmove function.

This leads arguments between 2GiB and 4GiB to be interpreted as larger than they are (specifically, a bit below 2^64), causing a buffer overflow.

Arguments between 4GiB and 6GiB are interpreted as 4GiB smaller than they should be, causing a possible information leak.

This commit fixes the bug: https://github.com/ocaml/ocaml/commit/659615c7b100a89eafe6253e7a5b9d84d0e8df74#diff-a97df53e3ebc59bb457191b496c90762 The function caml_bit_string is called indirectly from such functions as String.copy. String.copy for instance is supposed to be a "safe" function for which OCaml's memory safety guarantees apply.

Risk Scores
Base Score
9.1

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. 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 high impact on the availability of the system.

Threat Intelligence
8.3

Exploitation activity has been observed. Apply available patches or mitigations urgently.

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.

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