CVE-2024-7589 OpenSSH pre-authentication async signal safety issue

2024-08-1103:15:52

freebsd

github.com

cve-2024-7589; openssh; pre-authentication; async signal safety; race condition; unauthenticated remote code execution; root privileges

AI Score

7.9

Confidence

Low

EPSS

0.004

Percentile

73.8%

SSVC

Exploitation

none

Automatable

Technical Impact

total

JSON

A signal handler in sshd(8) may call a logging function that is not async-signal-safe. The signal handler is invoked when a client does not authenticate within the LoginGraceTime seconds (120 by default). This signal handler executes in the context of the sshd(8)'s privileged code, which is not sandboxed and runs with full root privileges.

This issue is another instance of the problem in CVE-2024-6387 addressed by FreeBSD-SA-24:04.openssh. The faulty code in this case is from the integration of blacklistd in OpenSSH in FreeBSD.

As a result of calling functions that are not async-signal-safe in the privileged sshd(8) context, a race condition exists that a determined attacker may be able to exploit to allow an unauthenticated remote code execution as root.

CNA Affected

[
  {
    "vendor": "FreeBSD",
    "modules": [
      "openssh"
    ],
    "product": "FreeBSD",
    "versions": [
      {
        "status": "affected",
        "version": "14.1-RELEASE",
        "lessThan": "p3",
        "versionType": "release"
      },
      {
        "status": "affected",
        "version": "14.0-RELEASE",
        "lessThan": "p9",
        "versionType": "release"
      },
      {
        "status": "affected",
        "version": "13.3-RELEASE",
        "lessThan": "p5",
        "versionType": "release"
      }
    ],
    "defaultStatus": "unknown"
  }
]

ADP Affected

[
  {
    "cpes": [
      "cpe:2.3:o:freebsd:freebsd:*:*:*:*:*:*:*:*"
    ],
    "vendor": "freebsd",
    "product": "freebsd",
    "versions": [
      {
        "status": "affected",
        "version": "13.3",
        "lessThan": "13.3_release_p5",
        "versionType": "custom"
      },
      {
        "status": "affected",
        "version": "14.0",
        "lessThan": "14.0_release_p9",
        "versionType": "custom"
      },
      {
        "status": "affected",
        "version": "14.1",
        "lessThan": "14.1_release_p3",
        "versionType": "custom"
      }
    ],
    "defaultStatus": "unknown"
  }
]