Vulnerability-Lookup

brew-libssh2-cve-2025-15661

Vulnerability from osv_homebrew

Published

2026-07-18 04:02

Modified

2026-07-18 04:02

Summary

libssh2 - Heap Buffer Over-read via sftp_symlink() in sftp.c

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

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

References

URL

Type

	https://github.com/CVEProject/cvelistV5/tree/main…	ADVISORY
	https://nvd.nist.gov/vuln/detail/CVE-2025-15661	ADVISORY
	https://www.vulncheck.com/advisories/libssh2-heap…	ADVISORY
	https://github.com/libssh2/libssh2/pull/1705	REPORT
	https://github.com/libssh2/libssh2/pull/1717	REPORT
	https://github.com/libssh2/libssh2/commit/2dae302…	FIX
	https://github.com/libssh2/libssh2	PACKAGE

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {
        "fix": "patch",
        "patches": [
          {
            "file": "Patches/libssh2/CVE-2025-15661.patch",
            "type": "backport"
          }
        ]
      },
      "package": {
        "ecosystem": "Homebrew",
        "name": "libssh2",
        "purl": "pkg:brew/libssh2"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.11.1_3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "source": "generated"
  },
  "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": "BREW-libssh2-CVE-2025-15661",
  "modified": "2026-07-18T04:02:33Z",
  "published": "2026-07-18T04:02:33Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/15xxx/CVE-2025-15661.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-15661"
    },
    {
      "type": "ADVISORY",
      "url": "https://www.vulncheck.com/advisories/libssh2-heap-buffer-over-read-via-sftp-symlink-in-sftp-c"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/libssh2/libssh2/pull/1705"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/libssh2/libssh2/pull/1717"
    },
    {
      "type": "FIX",
      "url": "https://github.com/libssh2/libssh2/commit/2dae3024897e1898d389835151f4e9606227721d"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/libssh2/libssh2"
    }
  ],
  "schema_version": "1.7.3",
  "severity": [
    {
      "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"
    }
  ],
  "summary": "libssh2 - Heap Buffer Over-read via sftp_symlink() in sftp.c",
  "upstream": [
    "CVE-2025-15661"
  ]
}

CVE-2025-15661 (GCVE-0-2025-15661)

Vulnerability from cvelistv5 – Published: 2026-06-18 20:18 – Updated: 2026-07-14 22:25 X_Open Source

Title

libssh2 - Heap Buffer Over-read via sftp_symlink() in sftp.c

Summary

Severity

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

6.5 (Medium)


                        
                          CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:H

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-06-22 18:07 UTC

CWE

CWE-125 - Out-of-bounds Read

Assigner

VulnCheck mitre root

References

4 references

URL	Tags
https://github.com/libssh2/libssh2/pull/1705	issue-tracking
https://github.com/libssh2/libssh2/pull/1717	issue-tracking
https://github.com/libssh2/libssh2/commit/2dae302…	patch
https://www.vulncheck.com/advisories/libssh2-heap…	third-party-advisory

Impacted products

1 product

Vendor	Product	Version
libssh2	libssh2	Affected: 0 , ≤ 1.11.1 (semver) Unaffected: 2dae3024897e1898d389835151f4e9606227721d (git) cpe:2.3:a:libssh2:libssh2::::::::

Date Public

2025-10-06 00:00

Credits

Joshua Rogers Tristan Madani (@TristanInSec)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2025-15661",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-06-22T18:07:05.411976Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-06-22T18:07:10.941Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "affected",
          "packageURL": "pkg:github/libssh2/libssh2",
          "product": "libssh2",
          "repo": "https://github.com/libssh2/libssh2",
          "vendor": "libssh2",
          "versions": [
            {
              "lessThanOrEqual": "1.11.1",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "2dae3024897e1898d389835151f4e9606227721d",
              "versionType": "git"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:a:libssh2:libssh2:*:*:*:*:*:*:*:*",
                  "versionEndIncluding": "1.11.1",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
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      "credits": [
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          "lang": "en",
          "type": "finder",
          "value": "Joshua Rogers"
        },
        {
          "lang": "en",
          "type": "reporter",
          "value": "Tristan Madani (@TristanInSec)"
        }
      ],
      "datePublic": "2025-10-06T00:00:00.000Z",
      "descriptions": [
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        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "HIGH",
            "attackRequirements": "NONE",
            "attackVector": "NETWORK",
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            "baseSeverity": "HIGH",
            "exploitMaturity": "NOT_DEFINED",
            "privilegesRequired": "NONE",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "valueDensity": "NOT_DEFINED",
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            "version": "4.0",
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            "vulnConfidentialityImpact": "LOW",
            "vulnIntegrityImpact": "NONE",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
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          "scenarios": [
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              "lang": "en",
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        {
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            "availabilityImpact": "HIGH",
            "baseScore": 6.5,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "LOW",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:H",
            "version": "3.1"
          },
          "format": "CVSS",
          "scenarios": [
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              "lang": "en",
              "value": "GENERAL"
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      "problemTypes": [
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          "descriptions": [
            {
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              "description": "Out-of-bounds Read",
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      "providerMetadata": {
        "dateUpdated": "2026-07-14T22:25:35.894Z",
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          "tags": [
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          "url": "https://github.com/libssh2/libssh2/pull/1705"
        },
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        },
        {
          "tags": [
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          "url": "https://www.vulncheck.com/advisories/libssh2-heap-buffer-over-read-via-sftp-symlink-in-sftp-c"
        }
      ],
      "source": {
        "discovery": "UNKNOWN"
      },
      "tags": [
        "x_open-source"
      ],
      "title": "libssh2 - Heap Buffer Over-read via sftp_symlink() in sftp.c",
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  "cveMetadata": {
    "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
    "assignerShortName": "VulnCheck",
    "cveId": "CVE-2025-15661",
    "datePublished": "2026-06-18T20:18:29.475Z",
    "dateReserved": "2026-06-18T20:12:38.095Z",
    "dateUpdated": "2026-07-14T22:25:35.894Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.