LSH file descriptor leak information disclosure and denial of service

lsh-file-descriptor-leak (24263) The risk level is classified as MediumMedium Risk


LSH leaks file descriptors of the random generator seed file to user shells that are started by lshd. This could allow a local attacker to cause a denial of service by truncating the seed file, or obtain sensitive information that could be used to crack session keys.


Obtain Information


For vendor-supplied patch, refer to the lsh-bugs Mailing List posting dated Fri Jan 20 17:44:07 CET 2006. See References.

For Debian GNU/Linux:
Refer to DSA-956-1 for patch, upgrade, or suggested workaround information. See References.


  • lsh Web page: LSH - a GNU implementation of the Secure Shells protocols.
  • lsh-bugs Mailing List, Fri Jan 20 17:44:07 CET 2006: SECURITY: lshd leaks fd:s to user shells.
  • BID-16357: LSH Seed File File Descriptor Leakage Vulnerability
  • CVE-2006-0353: unix_random.c in lshd for lsh 2.0.1 leaks file descriptors related to the randomness generator, which allows local users to cause a denial of service by truncating the seed file, which prevents the server from starting, or obtain sensitive seed information that could be used to crack keys.
  • DSA-956: lsh-server -- filedescriptor leak
  • OSVDB ID: 22695: LSH lshd Seed-file File Descriptor Leak
  • SA18564: LSH lshd Seed-file File Descriptor Leak Vulnerability

Platforms Affected:

  • Debian Debian Linux 3.1
  • GNU LSH 2.0.1


Jan 20, 2006

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