UBUNTU-CVE-2026-66032 (CVE-2026-66032)

Vulnerability from osv_ubuntu – Published: 2026-07-24 17:17 – Updated: 2026-09-23 05:00 – Source website
VLAI
Details

libssh2 through 1.11.1, fixed in commit 5e47761, contains a double-free vulnerability in the sftp_open() function in src/sftp.c that allows a malicious SSH server to corrupt the heap of any authenticated client opening an SFTP session. When a server responds to SSH_FXP_OPEN with SSH_FXP_STATUS containing FX_OK, the response data buffer is freed, and if a subsequent sftp_packet_require() call returns a specific error such as LIBSSH2_ERROR_CHANNEL_PACKET_EXCEEDED, the same pointer is freed a second time, enabling tcache dup conditions on glibc systems that allow overlapping allocations and function pointer overwrites.

Severity
8.8 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
8.7 (High)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
N/A (UNKNOWN)
medium
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "availability": "Available with Ubuntu Pro with Legacy support add-on: https://ubuntu.com/pro",
        "binaries": [
          {
            "binary_name": "libssh2-1",
            "binary_version": "1.4.3-2ubuntu0.2+esm4"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:14.04:LTS",
        "name": "libssh2",
        "purl": "pkg:deb/ubuntu/libssh2@1.4.3-2ubuntu0.2+esm4?arch=source\u0026distro=esm-infra-legacy/trusty"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.4.3-2ubuntu0.2+esm4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.4.3-1",
        "1.4.3-2",
        "1.4.3-2ubuntu0.1",
        "1.4.3-2ubuntu0.2",
        "1.4.3-2ubuntu0.2+esm1",
        "1.4.3-2ubuntu0.2+esm2",
        "1.4.3-2ubuntu0.2+esm3"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "Available with Ubuntu Pro with Legacy support add-on: https://ubuntu.com/pro",
        "binaries": [
          {
            "binary_name": "libssh2-1",
            "binary_version": "1.5.0-2ubuntu0.1+esm3"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:16.04:LTS",
        "name": "libssh2",
        "purl": "pkg:deb/ubuntu/libssh2@1.5.0-2ubuntu0.1+esm3?arch=source\u0026distro=esm-apps-legacy/xenial"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.5.0-2ubuntu0.1+esm3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.5.0-2",
        "1.5.0-2ubuntu0.1",
        "1.5.0-2ubuntu0.1+esm1",
        "1.5.0-2ubuntu0.1+esm2"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "Available with Ubuntu Pro: https://ubuntu.com/pro",
        "binaries": [
          {
            "binary_name": "libssh2-1",
            "binary_version": "1.8.0-1ubuntu0.1+esm1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:18.04:LTS",
        "name": "libssh2",
        "purl": "pkg:deb/ubuntu/libssh2@1.8.0-1ubuntu0.1+esm1?arch=source\u0026distro=esm-apps/bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.8.0-1ubuntu0.1+esm1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.8.0-1",
        "1.8.0-1ubuntu0.1"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "Available with Ubuntu Pro: https://ubuntu.com/pro",
        "binaries": [
          {
            "binary_name": "libssh2-1",
            "binary_version": "1.8.0-2.1ubuntu0.1+esm1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:20.04:LTS",
        "name": "libssh2",
        "purl": "pkg:deb/ubuntu/libssh2@1.8.0-2.1ubuntu0.1+esm1?arch=source\u0026distro=esm-apps/focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.8.0-2.1ubuntu0.1+esm1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.8.0-2.1build1",
        "1.8.0-2.1ubuntu0.1"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "libssh2-1",
            "binary_version": "1.10.0-3ubuntu0.1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:22.04:LTS",
        "name": "libssh2",
        "purl": "pkg:deb/ubuntu/libssh2@1.10.0-3ubuntu0.1?arch=source\u0026distro=jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.10.0-3ubuntu0.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.9.0-3",
        "1.10.0-2",
        "1.10.0-2build1",
        "1.10.0-3"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "libssh2-1t64",
            "binary_version": "1.11.0-4.1ubuntu0.24.04.4"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:24.04:LTS",
        "name": "libssh2",
        "purl": "pkg:deb/ubuntu/libssh2@1.11.0-4.1ubuntu0.24.04.4?arch=source\u0026distro=noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.11.0-4.1ubuntu0.24.04.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.11.0-2",
        "1.11.0-3",
        "1.11.0-4",
        "1.11.0-4.1build1",
        "1.11.0-4.1build2",
        "1.11.0-4.1ubuntu0.24.04.1",
        "1.11.0-4.1ubuntu0.24.04.2",
        "1.11.0-4.1ubuntu0.24.04.3"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "libssh2-1t64",
            "binary_version": "1.11.1-1ubuntu0.26.04.4"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:26.04:LTS",
        "name": "libssh2",
        "purl": "pkg:deb/ubuntu/libssh2@1.11.1-1ubuntu0.26.04.4?arch=source\u0026distro=resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.11.1-1ubuntu0.26.04.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.11.1-1build1",
        "1.11.1-1build2",
        "1.11.1-1ubuntu0.26.04.1",
        "1.11.1-1ubuntu0.26.04.2",
        "1.11.1-1ubuntu0.26.04.3"
      ]
    }
  ],
  "aliases": [],
  "details": "libssh2 through 1.11.1, fixed in commit 5e47761, contains a double-free vulnerability in the sftp_open() function in src/sftp.c that allows a malicious SSH server to corrupt the heap of any authenticated client opening an SFTP session. When a server responds to SSH_FXP_OPEN with SSH_FXP_STATUS containing FX_OK, the response data buffer is freed, and if a subsequent sftp_packet_require() call returns a specific error such as LIBSSH2_ERROR_CHANNEL_PACKET_EXCEEDED, the same pointer is freed a second time, enabling tcache dup conditions on glibc systems that allow overlapping allocations and function pointer overwrites.",
  "id": "UBUNTU-CVE-2026-66032",
  "modified": "2026-09-23T05:00:46Z",
  "published": "2026-07-24T17:17:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-66032"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-66032"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/libssh2/libssh2/pull/2180"
    },
    {
      "type": "REPORT",
      "url": "https://www.vulncheck.com/advisories/libssh2-double-free-heap-corruption-via-sftp-open"
    },
    {
      "type": "ADVISORY",
      "url": "https://ubuntu.com/security/notices/USN-8722-1"
    },
    {
      "type": "ADVISORY",
      "url": "https://ubuntu.com/security/notices/USN-8799-1"
    }
  ],
  "related": [
    "USN-8722-1",
    "USN-8799-1"
  ],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-66032"
  ]
}



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