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HIGH — CVSS 8.1

OpenSSH Signal Handler Race Condition (regreSSHion)

Signal handler race condition vulnerability in OpenSSH's server (sshd) allowing unauthenticated remote code execution as root on glibc-based Linux systems.

Status
Vendor Patched
Reported / Disclosed
2024

Impact

  • Signal race condition inside SIGALRM handler calling async-signal-unsafe memory allocation routines.
  • Complete root execution on default Linux enterprise servers without user interaction.
  • Regression of historic CVE-2006-5051 affecting modern OpenSSH versions 8.5p1 through 9.7p1.

Timeline

  1. MAY 2024

    Discovered and responsibly reported by Qualys Threat Research Unit.

  2. JULY 1, 2024

    OpenSSH 9.8p1 released addressing signal safety in sshd daemon.

  3. JULY 2024

    Distribution-wide backports rolled out across Ubuntu, Debian, RedHat, and Alpine.

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