ubuntu-cve-2025-15661
Vulnerability from osv_ubuntu
Published
2026-06-18 21:16
Modified
2026-06-30 16:13
Summary
Details

libssh2 through 1.11.1, fixed in commit 2dae302, contains an out-of-bounds heap read vulnerability in the sftp_symlink() function in src/sftp.c that allows a malicious SSH server or man-in-the-middle attacker to disclose heap memory contents or cause a crash by sending a crafted SSH_FXP_NAME response. Attackers can supply a link_len value larger than the actual packet data in SSH_FXP_NAME responses for SFTP READLINK and REALPATH operations, triggering a heap buffer over-read of up to target_len minus one bytes due to the missing validation of available packet buffer size before the memcpy operation.

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

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libssh2-1",
            "binary_version": "1.4.3-2ubuntu0.2+esm3"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:14.04:LTS",
        "name": "libssh2",
        "purl": "pkg:deb/ubuntu/libssh2@1.4.3-2ubuntu0.2+esm3?arch=source\u0026distro=esm-infra-legacy/trusty"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "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": {
        "binaries": [
          {
            "binary_name": "libssh2-1",
            "binary_version": "1.5.0-2ubuntu0.1+esm2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:16.04:LTS",
        "name": "libssh2",
        "purl": "pkg:deb/ubuntu/libssh2@1.5.0-2ubuntu0.1+esm2?arch=source\u0026distro=esm-apps/xenial"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "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": {
        "binaries": [
          {
            "binary_name": "libssh2-1",
            "binary_version": "1.8.0-1ubuntu0.1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:18.04:LTS",
        "name": "libssh2",
        "purl": "pkg:deb/ubuntu/libssh2@1.8.0-1ubuntu0.1?arch=source\u0026distro=bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.8.0-1",
        "1.8.0-1ubuntu0.1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libssh2-1",
            "binary_version": "1.8.0-2.1ubuntu0.1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:20.04:LTS",
        "name": "libssh2",
        "purl": "pkg:deb/ubuntu/libssh2@1.8.0-2.1ubuntu0.1?arch=source\u0026distro=focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.8.0-2.1build1",
        "1.8.0-2.1ubuntu0.1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libssh2-1",
            "binary_version": "1.10.0-3"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:22.04:LTS",
        "name": "libssh2",
        "purl": "pkg:deb/ubuntu/libssh2@1.10.0-3?arch=source\u0026distro=jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "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": "1.11.0-4.1ubuntu0.24.04.2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:24.04:LTS",
        "name": "libssh2",
        "purl": "pkg:deb/ubuntu/libssh2@1.11.0-4.1ubuntu0.24.04.2?arch=source\u0026distro=noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.11.0-4.1ubuntu0.24.04.2"
            }
          ],
          "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"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "libssh2-1t64",
            "binary_version": "1.11.1-1ubuntu0.25.10.2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:25.10",
        "name": "libssh2",
        "purl": "pkg:deb/ubuntu/libssh2@1.11.1-1ubuntu0.25.10.2?arch=source\u0026distro=questing"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.11.1-1ubuntu0.25.10.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.11.1-1",
        "1.11.1-1build1",
        "1.11.1-1ubuntu0.25.10.1"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "libssh2-1t64",
            "binary_version": "1.11.1-1ubuntu0.26.04.2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:26.04:LTS",
        "name": "libssh2",
        "purl": "pkg:deb/ubuntu/libssh2@1.11.1-1ubuntu0.26.04.2?arch=source\u0026distro=resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.11.1-1ubuntu0.26.04.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.11.1-1build1",
        "1.11.1-1build2",
        "1.11.1-1ubuntu0.26.04.1"
      ]
    }
  ],
  "aliases": [],
  "details": "libssh2 through 1.11.1, fixed in commit 2dae302, contains an out-of-bounds heap read vulnerability in the sftp_symlink() function in src/sftp.c that allows a malicious SSH server or man-in-the-middle attacker to disclose heap memory contents or cause a crash by sending a crafted SSH_FXP_NAME response. Attackers can supply a link_len value larger than the actual packet data in SSH_FXP_NAME responses for SFTP READLINK and REALPATH operations, triggering a heap buffer over-read of up to target_len minus one bytes due to the missing validation of available packet buffer size before the memcpy operation.",
  "id": "UBUNTU-CVE-2025-15661",
  "modified": "2026-06-30T16:13:31Z",
  "published": "2026-06-18T21:16:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2025-15661"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2025-15661"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/libssh2/libssh2/pull/1705"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/libssh2/libssh2/pull/1717"
    },
    {
      "type": "REPORT",
      "url": "https://www.vulncheck.com/advisories/libssh2-heap-buffer-over-read-via-sftp-symlink-in-sftp-c"
    },
    {
      "type": "ADVISORY",
      "url": "https://ubuntu.com/security/notices/USN-8486-1"
    }
  ],
  "related": [
    "USN-8486-1"
  ],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2025-15661"
  ]
}



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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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