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Security Advisory

USN-6138-1: libssh vulnerabilities




Canonical Ubuntu

Versions Affected

  • Canonical Ubuntu 22.04


Philip Turnbull discovered that libssh incorrectly handled rekeying with algorithm guessing. A remote attacker could use this issue to cause libssh to crash, resulting in a denial of service, or possibly execute arbitrary code. (CVE-2023-1667) Kevin Backhouse discovered that libssh incorrectly handled verifying data signatures. A remote attacker could possibly use this issue to bypass authorization. (CVE-2023-2283) Update Instructions: Run `sudo pro fix USN-6138-1` to fix the vulnerability. The problem can be corrected by updating your system to the following package versions: libssh-gcrypt-dev – 0.9.6-2ubuntu0.22.04.1 libssh-doc – 0.9.6-2ubuntu0.22.04.1 libssh-4 – 0.9.6-2ubuntu0.22.04.1 libssh-dev – 0.9.6-2ubuntu0.22.04.1 libssh-gcrypt-4 – 0.9.6-2ubuntu0.22.04.1 No subscription required

CVEs contained in this USN include: CVE-2023-1667, CVE-2023-2283.

Affected Cloud Foundry Products and Versions

Severity is medium unless otherwise noted.

  • cflinuxfs4
    • All versions prior to 1.16.0
  • Jammy Stemcells
    • 1.x versions prior to 1.147
    • All other stemcells not listed.
  • CF Deployment
    • All versions with Jammy Stemcells prior to 1.147


Users of affected products are strongly encouraged to follow the mitigations below. The Cloud Foundry project recommends upgrading the following releases:

  • cflinuxfs4
    • Upgrade all versions to 1.16.0 or greater
  • Jammy Stemcells
    • Upgrade 1.x versions to 1.147 or greater
    • All other stemcells should be upgraded to the latest version available on
  • CF Deployment
    • For all versions, upgrade Jammy Stemcells to 1.147 or greater


2023-06-29: Initial vulnerability report published.

Cloud Foundry Foundation Security Team Profile Image

Cloud Foundry Foundation Security Team, AUTHOR