OpenBSD select() system call buffer overflow

openbsd-select-bo (9809) The risk level is classified as HighHigh Risk


OpenBSD is vulnerable to a buffer overflow in the select() system call, caused by improper boundary checking of user-supplied input. By passing a malformed size parameter to select(), a local attacker could overwrite kernel memory and gain elevated privileges on the system.


Gain Privileges


Upgrade to the latest version of OpenBSD (3.0-stable or 3.1-stable dated 2002-08-11 17:00 EDT or later), as listed in OpenBSD Security Advisory ( See References.

— OR —

Apply the patch for this vulnerability, as listed in OpenBSD Security Advisory ( See References.


  • Full-Disclosure Mailing List, Sun Aug 11 2002 - 16:09:03 CDT: OpenBSD Security Advisory: Select Boundary Condition.
  • OpenBSD Web site: OpenBSD.
  • BID-5442: OpenBSD select() Buffer Overflow Vulnerability
  • CVE-2002-1420: Integer signedness error in select() on OpenBSD 3.1 and earlier allows local users to overwrite arbitrary kernel memory via a negative value for the size parameter, which satisfies the boundary check as a signed integer, but is later used as an unsigned integer during a data copying operation.
  • OSVDB ID: 7554: OpenBSD select() Integer Signedness Arbitrary Kernel Memory Overwrite
  • US-CERT VU#259787: OpenBSD contains buffer overflow in select call

Platforms Affected:

  • OpenBSD OpenBSD 3.0
  • OpenBSD OpenBSD 3.1


Aug 11, 2002

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