libssh2 — security advisory

{
  "id": "b6a91dc25ee81b017622bfcaf37602160100b2e33660a96cfb473fbd4c849a05",
  "url": "https://osv.dev/vulnerability/DEBIAN-CVE-2025-15661",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "DEBIAN-CVE-2025-15661",
    "summary": "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.",
    "evidence": "osv:DEBIAN-CVE-2025-15661",
    "products": [
      {
        "name": {
          "value": "libssh2",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "1.10.0-3+deb12u1",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": [
          {
            "value": "1.10.0-3",
            "evidence": "/affected/0/versions"
          }
        ]
      },
      {
        "name": {
          "value": "libssh2",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "1.11.1-1+deb13u1",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": [
          {
            "value": "1.11.1-1",
            "evidence": "/affected/1/versions"
          }
        ]
      },
      {
        "name": {
          "value": "libssh2",
          "evidence": "/affected/2/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "1.11.1-4",
            "evidence": "/affected/2/ranges"
          }
        ],
        "affected_versions": [
          {
            "value": "1.11.1-1",
            "evidence": "/affected/2/versions"
          },
          {
            "value": "1.11.1-2",
            "evidence": "/affected/2/versions"
          },
          {
            "value": "1.11.1-3",
            "evidence": "/affected/2/versions"
          }
        ]
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "DEBIAN-CVE-2025-15661",
      "aliases": [
        "DEBIAN-CVE-2025-15661"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "1.10.0-3+deb12u1"
                }
              ]
            }
          ],
          "package": {
            "name": "libssh2",
            "purl": "pkg:deb/debian/libssh2?arch=source&distro=bookworm",
            "ecosystem": "Debian:12"
          },
          "versions": [
            "1.10.0-3"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2025-15661.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "1.11.1-1+deb13u1"
                }
              ]
            }
          ],
          "package": {
            "name": "libssh2",
            "purl": "pkg:deb/debian/libssh2?arch=source&distro=trixie",
            "ecosystem": "Debian:13"
          },
          "versions": [
            "1.11.1-1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2025-15661.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "1.11.1-4"
                }
              ]
            }
          ],
          "package": {
            "name": "libssh2",
            "purl": "pkg:deb/debian/libssh2?arch=source&distro=forky",
            "ecosystem": "Debian:14"
          },
          "versions": [
            "1.11.1-1",
            "1.11.1-2",
            "1.11.1-3"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2025-15661.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        }
      ],
      "modified": "2026-10-13T09:47:38.408513534Z",
      "provider": "osv",
      "upstream": [
        "CVE-2025-15661"
      ],
      "references": [
        "https://security-tracker.debian.org/tracker/CVE-2025-15661"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2025-15661",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 307580,
  "published_at": "2026-06-18T21:16:27.143+00:00"
}