Vulnerability-Lookup

GHSA-4J4Q-473W-9Q2R

Vulnerability from github – Published: 2026-05-20 03:31 – Updated: 2026-05-20 03:31

Details

Rsync version 3.4.2 and prior contain an authorization bypass vulnerability in the rsync daemon's hostname-based access control list enforcement when configured with chroot. Attackers can bypass hostname-based deny rules by controlling the PTR record for their source IP address, allowing connections from hostnames that administrators intended to deny when reverse DNS resolution fails and defaults to UNKNOWN.

Severity

4.8 (Medium)


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

6.3 (Medium)


                  
                    CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

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JSON

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{
  "affected": [],
  "aliases": [
    "CVE-2026-43617"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-289"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-05-20T02:16:36Z",
    "severity": "MODERATE"
  },
  "details": "Rsync version\u00a03.4.2 and prior contain an authorization bypass vulnerability in the rsync daemon\u0027s hostname-based access control list enforcement when configured with chroot. Attackers can bypass hostname-based deny rules by controlling the PTR record for their source IP address, allowing connections from hostnames that administrators intended to deny when reverse DNS resolution fails and defaults to UNKNOWN.",
  "id": "GHSA-4j4q-473w-9q2r",
  "modified": "2026-05-20T03:31:33Z",
  "published": "2026-05-20T03:31:33Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/RsyncProject/rsync/security/advisories/GHSA-rjfm-3w2m-jf4f"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-43617"
    },
    {
      "type": "WEB",
      "url": "https://github.com/RsyncProject/rsync/releases/tag/v3.4.3"
    },
    {
      "type": "WEB",
      "url": "https://www.vulncheck.com/advisories/rsync-authorization-bypass-via-hostname-resolution"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
      "type": "CVSS_V4"
    }
  ]
}

CVE-2026-43617 (GCVE-0-2026-43617)

Vulnerability from cvelistv5 – Published: 2026-05-20 00:52 – Updated: 2026-05-20 15:45

Title

Rsync < 3.4.3 Authorization Bypass via Hostname Resolution

Summary

Severity

6.3 (Medium)


                        
                          CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

4.8 (Medium)


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

CWE

CWE-289 - Authentication Bypass by Alternate Name

Assigner

VulnCheck

References

3 references

URL	Tags
https://github.com/RsyncProject/rsync/security/ad…	vendor-advisory
https://github.com/RsyncProject/rsync/releases/ta…	release-notes
https://www.vulncheck.com/advisories/rsync-author…	third-party-advisory

Impacted products

1 product

Vendor	Product	Version
RsyncProject	rsync	Affected: 0 , < 3.4.3 (semver)

Date Public

2026-05-19 00:00

Credits

Joshua Rogers (@MegaManSec)

Show details on NVD website

JSON

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{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-43617",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-05-20T13:24:57.595855Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-05-20T15:45:40.806Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
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          "defaultStatus": "unaffected",
          "product": "rsync",
          "repo": "https://github.com/RsyncProject/rsync",
          "vendor": "RsyncProject",
          "versions": [
            {
              "lessThan": "3.4.3",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Joshua Rogers (@MegaManSec)"
        }
      ],
      "datePublic": "2026-05-19T00:00:00.000Z",
      "descriptions": [
        {
          "lang": "en",
          "value": "Rsync version\u00a03.4.2 and prior contain an authorization bypass vulnerability in the rsync daemon\u0027s hostname-based access control list enforcement when configured with chroot. Attackers can bypass hostname-based deny rules by controlling the PTR record for their source IP address, allowing connections from hostnames that administrators intended to deny when reverse DNS resolution fails and defaults to UNKNOWN."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "HIGH",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 6.3,
            "baseSeverity": "MEDIUM",
            "exploitMaturity": "NOT_DEFINED",
            "privilegesRequired": "NONE",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
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            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "LOW",
            "vulnIntegrityImpact": "LOW",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
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          "scenarios": [
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              "lang": "en",
              "value": "GENERAL"
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            "baseScore": 4.8,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "LOW",
            "integrityImpact": "LOW",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N",
            "version": "3.1"
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          "format": "CVSS",
          "scenarios": [
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              "lang": "en",
              "value": "GENERAL"
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      ],
      "problemTypes": [
        {
          "descriptions": [
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              "cweId": "CWE-289",
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              "lang": "en",
              "type": "CWE"
            }
          ]
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      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-20T00:52:38.965Z",
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      },
      "references": [
        {
          "tags": [
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          ],
          "url": "https://github.com/RsyncProject/rsync/security/advisories/GHSA-rjfm-3w2m-jf4f"
        },
        {
          "tags": [
            "release-notes"
          ],
          "url": "https://github.com/RsyncProject/rsync/releases/tag/v3.4.3"
        },
        {
          "tags": [
            "third-party-advisory"
          ],
          "url": "https://www.vulncheck.com/advisories/rsync-authorization-bypass-via-hostname-resolution"
        }
      ],
      "source": {
        "discovery": "EXTERNAL"
      },
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  "cveMetadata": {
    "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
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    "cveId": "CVE-2026-43617",
    "datePublished": "2026-05-20T00:52:38.965Z",
    "dateReserved": "2026-05-01T18:22:45.639Z",
    "dateUpdated": "2026-05-20T15:45:40.806Z",
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}

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.

Action not permitted

GHSA-4J4Q-473W-9Q2R

CVE-2026-43617 (GCVE-0-2026-43617)

Tags

Sightings

Nomenclature