Vulnerability-Lookup

UBUNTU-CVE-2026-70455 (CVE-2026-70455)

Vulnerability from osv_ubuntu – Published: 2026-08-13 15:19 – Updated: 2026-08-19 11:09 – Source website

Details

rsync 3.4.2 before 3.5.0 contains a denial of service vulnerability that allows a remote sender to exhaust system resources by specifying the --zt short alias for --compress-threads, which bypasses the refuse options directive's string matching on long option names. Attackers can specify --zt=N with a large value to spawn an unbounded number of Zstandard worker threads on the receiver, exhausting available thread and memory resources.

Severity

7.5 (High)


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

8.7 (High)


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

N/A (UNKNOWN)


                    
                      medium

References

URL

Type

	https://ubuntu.com/security/CVE-2026-70455	REPORT
	https://www.cve.org/CVERecord?id=CVE-2026-70455	REPORT
	https://download.samba.org/pub/rsync/NEWS#3.5.0	REPORT

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "rsync",
            "binary_version": "3.1.0-2ubuntu0.4+esm4"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:14.04:LTS",
        "name": "rsync",
        "purl": "pkg:deb/ubuntu/rsync@3.1.0-2ubuntu0.4+esm4?arch=source\u0026distro=esm-infra-legacy/trusty"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "3.0.9-4ubuntu1",
        "3.1.0-2",
        "3.1.0-2ubuntu0.1",
        "3.1.0-2ubuntu0.2",
        "3.1.0-2ubuntu0.3",
        "3.1.0-2ubuntu0.4",
        "3.1.0-2ubuntu0.4+esm1",
        "3.1.0-2ubuntu0.4+esm2",
        "3.1.0-2ubuntu0.4+esm3",
        "3.1.0-2ubuntu0.4+esm4"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "rsync",
            "binary_version": "3.1.1-3ubuntu1.3+esm6"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:16.04:LTS",
        "name": "rsync",
        "purl": "pkg:deb/ubuntu/rsync@3.1.1-3ubuntu1.3+esm6?arch=source\u0026distro=esm-infra-legacy/xenial"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "3.1.1-3",
        "3.1.1-3ubuntu1",
        "3.1.1-3ubuntu1.1",
        "3.1.1-3ubuntu1.2",
        "3.1.1-3ubuntu1.3",
        "3.1.1-3ubuntu1.3+esm1",
        "3.1.1-3ubuntu1.3+esm2",
        "3.1.1-3ubuntu1.3+esm3",
        "3.1.1-3ubuntu1.3+esm4",
        "3.1.1-3ubuntu1.3+esm5",
        "3.1.1-3ubuntu1.3+esm6"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "rsync",
            "binary_version": "3.1.2-2.1ubuntu1.6+esm4"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:18.04:LTS",
        "name": "rsync",
        "purl": "pkg:deb/ubuntu/rsync@3.1.2-2.1ubuntu1.6+esm4?arch=source\u0026distro=esm-infra/bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "3.1.2-2",
        "3.1.2-2.1",
        "3.1.2-2.1ubuntu1",
        "3.1.2-2.1ubuntu1.1",
        "3.1.2-2.1ubuntu1.2",
        "3.1.2-2.1ubuntu1.3",
        "3.1.2-2.1ubuntu1.4",
        "3.1.2-2.1ubuntu1.5",
        "3.1.2-2.1ubuntu1.6",
        "3.1.2-2.1ubuntu1.6+esm1",
        "3.1.2-2.1ubuntu1.6+esm2",
        "3.1.2-2.1ubuntu1.6+esm3",
        "3.1.2-2.1ubuntu1.6+esm4"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "rsync",
            "binary_version": "3.1.3-8ubuntu0.9+esm2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:20.04:LTS",
        "name": "rsync",
        "purl": "pkg:deb/ubuntu/rsync@3.1.3-8ubuntu0.9+esm2?arch=source\u0026distro=esm-infra/focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "3.1.3-6",
        "3.1.3-8",
        "3.1.3-8ubuntu0.1",
        "3.1.3-8ubuntu0.2",
        "3.1.3-8ubuntu0.3",
        "3.1.3-8ubuntu0.4",
        "3.1.3-8ubuntu0.5",
        "3.1.3-8ubuntu0.7",
        "3.1.3-8ubuntu0.8",
        "3.1.3-8ubuntu0.9",
        "3.1.3-8ubuntu0.9+esm1",
        "3.1.3-8ubuntu0.9+esm2"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "rsync",
            "binary_version": "3.2.7-0ubuntu0.22.04.7"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:22.04:LTS",
        "name": "rsync",
        "purl": "pkg:deb/ubuntu/rsync@3.2.7-0ubuntu0.22.04.7?arch=source\u0026distro=jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "3.2.3-4ubuntu1",
        "3.2.3-4ubuntu2",
        "3.2.3-8ubuntu1",
        "3.2.3-8ubuntu2",
        "3.2.3-8ubuntu3",
        "3.2.3-8ubuntu3.1",
        "3.2.7-0ubuntu0.22.04.2",
        "3.2.7-0ubuntu0.22.04.3",
        "3.2.7-0ubuntu0.22.04.4",
        "3.2.7-0ubuntu0.22.04.6",
        "3.2.7-0ubuntu0.22.04.7"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "rsync",
            "binary_version": "3.2.7-1ubuntu1.5"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:24.04:LTS",
        "name": "rsync",
        "purl": "pkg:deb/ubuntu/rsync@3.2.7-1ubuntu1.5?arch=source\u0026distro=noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "3.2.7-1",
        "3.2.7-1build1",
        "3.2.7-1build2",
        "3.2.7-1ubuntu1",
        "3.2.7-1ubuntu1.1",
        "3.2.7-1ubuntu1.2",
        "3.2.7-1ubuntu1.4",
        "3.2.7-1ubuntu1.5"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "rsync",
            "binary_version": "3.4.1+ds1-7ubuntu0.3"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:26.04:LTS",
        "name": "rsync",
        "purl": "pkg:deb/ubuntu/rsync@3.4.1+ds1-7ubuntu0.3?arch=source\u0026distro=resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "3.4.1+ds1-5ubuntu1",
        "3.4.1+ds1-6",
        "3.4.1+ds1-7",
        "3.4.1+ds1-7ubuntu0.2",
        "3.4.1+ds1-7ubuntu0.3"
      ]
    }
  ],
  "aliases": [],
  "details": "rsync 3.4.2 before 3.5.0\u00a0contains a denial of service vulnerability that allows a remote sender to exhaust system resources by specifying the --zt short alias for --compress-threads, which bypasses the refuse options directive\u0027s string matching on long option names. Attackers can specify --zt=N with a large value to spawn an unbounded number of Zstandard worker threads on the receiver, exhausting available thread and memory resources.",
  "id": "UBUNTU-CVE-2026-70455",
  "modified": "2026-08-19T11:09:40Z",
  "published": "2026-08-13T15:19:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-70455"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-70455"
    },
    {
      "type": "REPORT",
      "url": "https://download.samba.org/pub/rsync/NEWS#3.5.0"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-70455"
  ]
}

CVE-2026-70455 (GCVE-0-2026-70455)

Vulnerability from cvelistv5 – Published: 2026-08-13 14:45 – Updated: 2026-08-14 19:45

Title

rsync 3.4.2 < 3.5.0 DoS via --zt Zstandard Compression Thread Exhaustion

Summary

Severity

8.7 (High)


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

7.5 (High)


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

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-08-14 18:30 UTC

CWE

CWE-770 - Allocation of Resources Without Limits or Throttling

Assigner

VulnCheck mitre root Scorecard

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-dos-vi…	third-party-advisory

Impacted products

1 product

Vendor	Product	Version
RsyncProject	rsync	Affected: 3.4.2 , ≤ 3.4.4 (semver) Unaffected: 3.5.0 (semver) cpe:2.3:a:samba:rsync::::::::

Date Public

2026-08-12 00:00

Credits

fcasal

Show details on NVD website

JSON

To clipboard

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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.

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.

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UBUNTU-CVE-2026-70455 (CVE-2026-70455)

CVE-2026-70455 (GCVE-0-2026-70455)

Tags

Sightings

Nomenclature

Related by attack behaviour