CVE-2026-70455 (GCVE-0-2026-70455)
Vulnerability from cvelistv5 – Published: 2026-08-13 14:45 – Updated: 2026-08-14 19:45
VLAI
EPSS
VEX
Title
rsync 3.4.2 < 3.5.0 DoS via --zt Zstandard Compression Thread Exhaustion
Summary
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
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
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 | CPE status | |
|---|---|---|---|---|
| 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
{
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-70455",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "yes"
},
{
"Technical Impact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-08-14T18:30:20.676739Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-08-14T19:45:47.934Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"packageURL": "pkg:github/RsyncProject/rsync",
"product": "rsync",
"repo": "https://github.com/RsyncProject/rsync",
"vendor": "RsyncProject",
"versions": [
{
"lessThanOrEqual": "3.4.4",
"status": "affected",
"version": "3.4.2",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "3.5.0",
"versionType": "semver"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:a:samba:rsync:*:*:*:*:*:*:*:*",
"versionEndIncluding": "3.4.4",
"versionStartIncluding": "3.4.2",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"credits": [
{
"lang": "en",
"type": "finder",
"value": "fcasal"
}
],
"datePublic": "2026-08-12T00:00:00.000Z",
"descriptions": [
{
"lang": "en",
"supportingMedia": [
{
"base64": false,
"type": "text/html",
"value": "\u003cp\u003ersync 3.4.2 before 3.5.0\u0026nbsp;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\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.\u003c/p\u003e"
}
],
"value": "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."
}
],
"metrics": [
{
"cvssV4_0": {
"Automatable": "NOT_DEFINED",
"Recovery": "NOT_DEFINED",
"Safety": "NOT_DEFINED",
"attackComplexity": "LOW",
"attackRequirements": "NONE",
"attackVector": "NETWORK",
"baseScore": 8.7,
"baseSeverity": "HIGH",
"exploitMaturity": "NOT_DEFINED",
"privilegesRequired": "NONE",
"providerUrgency": "NOT_DEFINED",
"subAvailabilityImpact": "NONE",
"subConfidentialityImpact": "NONE",
"subIntegrityImpact": "NONE",
"userInteraction": "NONE",
"valueDensity": "NOT_DEFINED",
"vectorString": "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",
"version": "4.0",
"vulnAvailabilityImpact": "HIGH",
"vulnConfidentialityImpact": "NONE",
"vulnIntegrityImpact": "NONE",
"vulnerabilityResponseEffort": "NOT_DEFINED"
},
"format": "CVSS",
"scenarios": [
{
"lang": "en",
"value": "Remote sender specifies --zt=N (Zstandard short alias not covered by refuse options) to spawn unbounded worker threads on the receiver (VA:H)."
}
]
},
{
"cvssV3_1": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "HIGH",
"baseScore": 7.5,
"baseSeverity": "HIGH",
"confidentialityImpact": "NONE",
"integrityImpact": "NONE",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"version": "3.1"
},
"format": "CVSS",
"scenarios": [
{
"lang": "en",
"value": "CVSS 3.1 reference score."
}
]
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-770",
"description": "CWE-770 Allocation of Resources Without Limits or Throttling",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-14T16:51:20.314Z",
"orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
"shortName": "VulnCheck"
},
"references": [
{
"name": "GitHub Security Advisory (GHSA-rjvj-qgqg-cvx9)",
"tags": [
"vendor-advisory"
],
"url": "https://github.com/RsyncProject/rsync/security/advisories/GHSA-rjvj-qgqg-cvx9"
},
{
"name": "rsync 3.5.0 Release Notes",
"tags": [
"release-notes"
],
"url": "https://github.com/RsyncProject/rsync/releases/tag/v3.5.0"
},
{
"tags": [
"third-party-advisory"
],
"url": "https://www.vulncheck.com/advisories/rsync-dos-via-zt-zstandard-compression-thread-exhaustion"
}
],
"source": {
"discovery": "EXTERNAL"
},
"title": "rsync 3.4.2 \u003c 3.5.0 DoS via --zt Zstandard Compression Thread Exhaustion",
"x_generator": {
"engine": "Vulnogram 1.0.4"
}
}
},
"cveMetadata": {
"assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
"assignerShortName": "VulnCheck",
"cveId": "CVE-2026-70455",
"datePublished": "2026-08-13T14:45:11.164Z",
"dateReserved": "2026-08-04T14:52:23.814Z",
"dateUpdated": "2026-08-14T19:45:47.934Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"epss": {
"cve": "CVE-2026-70455",
"date": "2026-09-21",
"epss": "0.00566",
"percentile": "0.45488"
},
"microsoft_vex": {
"current_release_date": "2026-08-23T14:45:06.000Z",
"cve": "CVE-2026-70455",
"id": "msrc_CVE-2026-70455",
"initial_release_date": "2026-08-23T14:45:06.000Z",
"product_status:fixed": "1",
"product_status:known_affected": "1",
"source": "Microsoft CSAF VEX",
"status": "final",
"title": "rsync 3.4.2 \u003c 3.5.0 DoS via --zt Zstandard Compression Thread Exhaustion",
"url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-70455.json",
"version": "1"
},
"nvd": {
"cve": {
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"packageURL": "pkg:github/RsyncProject/rsync",
"product": "rsync",
"repo": "https://github.com/RsyncProject/rsync",
"vendor": "RsyncProject",
"versions": [
{
"lessThanOrEqual": "3.4.4",
"status": "affected",
"version": "3.4.2",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "3.5.0",
"versionType": "semver"
}
]
}
],
"source": "disclosure@vulncheck.com"
}
],
"configurations": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:a:samba:rsync:*:*:*:*:*:*:*:*",
"matchCriteriaId": "7DB8B451-2711-4228-9FAD-B669B1C4A1F4",
"versionEndExcluding": "3.5.0",
"versionStartIncluding": "3.4.2",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "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": "CVE-2026-70455",
"lastModified": "2026-08-31T15:12:33.367",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "HIGH",
"baseScore": 7.5,
"baseSeverity": "HIGH",
"confidentialityImpact": "NONE",
"integrityImpact": "NONE",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"version": "3.1"
},
"exploitabilityScore": 3.9,
"impactScore": 3.6,
"source": "disclosure@vulncheck.com",
"type": "Secondary"
}
],
"cvssMetricV40": [
{
"cvssData": {
"Automatable": "NOT_DEFINED",
"Recovery": "NOT_DEFINED",
"Safety": "NOT_DEFINED",
"attackComplexity": "LOW",
"attackRequirements": "NONE",
"attackVector": "NETWORK",
"availabilityRequirement": "NOT_DEFINED",
"baseScore": 8.7,
"baseSeverity": "HIGH",
"confidentialityRequirement": "NOT_DEFINED",
"exploitMaturity": "NOT_DEFINED",
"integrityRequirement": "NOT_DEFINED",
"modifiedAttackComplexity": "NOT_DEFINED",
"modifiedAttackRequirements": "NOT_DEFINED",
"modifiedAttackVector": "NOT_DEFINED",
"modifiedPrivilegesRequired": "NOT_DEFINED",
"modifiedSubAvailabilityImpact": "NOT_DEFINED",
"modifiedSubConfidentialityImpact": "NOT_DEFINED",
"modifiedSubIntegrityImpact": "NOT_DEFINED",
"modifiedUserInteraction": "NOT_DEFINED",
"modifiedVulnAvailabilityImpact": "NOT_DEFINED",
"modifiedVulnConfidentialityImpact": "NOT_DEFINED",
"modifiedVulnIntegrityImpact": "NOT_DEFINED",
"privilegesRequired": "NONE",
"providerUrgency": "NOT_DEFINED",
"subAvailabilityImpact": "NONE",
"subConfidentialityImpact": "NONE",
"subIntegrityImpact": "NONE",
"userInteraction": "NONE",
"valueDensity": "NOT_DEFINED",
"vectorString": "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/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",
"version": "4.0",
"vulnAvailabilityImpact": "HIGH",
"vulnConfidentialityImpact": "NONE",
"vulnIntegrityImpact": "NONE",
"vulnerabilityResponseEffort": "NOT_DEFINED"
},
"source": "disclosure@vulncheck.com",
"type": "Secondary"
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2026-70455",
"options": [
{
"exploitation": "none"
},
{
"automatable": "yes"
},
{
"technicalImpact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-08-14T18:30:20.676739Z",
"version": "2.0.3"
}
}
]
},
"published": "2026-08-13T15:19:59.197",
"references": [
{
"source": "disclosure@vulncheck.com",
"tags": [
"Product",
"Release Notes"
],
"url": "https://github.com/RsyncProject/rsync/releases/tag/v3.5.0"
},
{
"source": "disclosure@vulncheck.com",
"tags": [
"Vendor Advisory"
],
"url": "https://github.com/RsyncProject/rsync/security/advisories/GHSA-rjvj-qgqg-cvx9"
},
{
"source": "disclosure@vulncheck.com",
"tags": [
"Release Notes",
"Third Party Advisory"
],
"url": "https://www.vulncheck.com/advisories/rsync-dos-via-zt-zstandard-compression-thread-exhaustion"
}
],
"sourceIdentifier": "disclosure@vulncheck.com",
"vulnStatus": "Analyzed",
"weaknesses": [
{
"description": [
{
"lang": "en",
"value": "CWE-770"
}
],
"source": "disclosure@vulncheck.com",
"type": "Secondary"
}
]
}
},
"redhat_vex": {
"aggregate_severity": "Important",
"current_release_date": "2026-09-14T23:43:48+00:00",
"cve": "CVE-2026-70455",
"id": "CVE-2026-70455",
"initial_release_date": "2026-08-13T14:45:11.164000+00:00",
"product_status:fixed": "15",
"product_status:known_not_affected": "13",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "rsync: rsync: Denial of Service via Zstandard compression thread exhaustion",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-70455.json",
"version": "3"
},
"suse_vex": {
"aggregate_severity": "important",
"current_release_date": "2026-09-19T01:50:45Z",
"cve": "CVE-2026-70455",
"id": "CVE-2026-70455",
"initial_release_date": "2026-08-18T00:08:16Z",
"product_status:known_affected": "394",
"product_status:known_not_affected": "22",
"product_status:recommended": "30",
"source": "SUSE CSAF VEX",
"status": "interim",
"title": "SUSE CVE CVE-2026-70455",
"url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-70455.json",
"version": "11"
},
"vulnrichment": {
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-70455",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "yes"
},
{
"Technical Impact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-08-14T18:30:20.676739Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-08-14T18:30:21.730Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"packageURL": "pkg:github/RsyncProject/rsync",
"product": "rsync",
"repo": "https://github.com/RsyncProject/rsync",
"vendor": "RsyncProject",
"versions": [
{
"lessThanOrEqual": "3.4.4",
"status": "affected",
"version": "3.4.2",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "3.5.0",
"versionType": "semver"
}
]
}
],
"credits": [
{
"lang": "en",
"type": "finder",
"value": "fcasal"
}
],
"datePublic": "2026-08-12T00:00:00.000Z",
"descriptions": [
{
"lang": "en",
"supportingMedia": [
{
"base64": false,
"type": "text/html",
"value": "\u003cp\u003ersync 3.4.2 before 3.5.0\u0026nbsp;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\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.\u003c/p\u003e"
}
],
"value": "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."
}
],
"metrics": [
{
"cvssV4_0": {
"Automatable": "NOT_DEFINED",
"Recovery": "NOT_DEFINED",
"Safety": "NOT_DEFINED",
"attackComplexity": "LOW",
"attackRequirements": "NONE",
"attackVector": "NETWORK",
"baseScore": 8.7,
"baseSeverity": "HIGH",
"exploitMaturity": "NOT_DEFINED",
"privilegesRequired": "NONE",
"providerUrgency": "NOT_DEFINED",
"subAvailabilityImpact": "NONE",
"subConfidentialityImpact": "NONE",
"subIntegrityImpact": "NONE",
"userInteraction": "NONE",
"valueDensity": "NOT_DEFINED",
"vectorString": "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",
"version": "4.0",
"vulnAvailabilityImpact": "HIGH",
"vulnConfidentialityImpact": "NONE",
"vulnIntegrityImpact": "NONE",
"vulnerabilityResponseEffort": "NOT_DEFINED"
},
"format": "CVSS",
"scenarios": [
{
"lang": "en",
"value": "Remote sender specifies --zt=N (Zstandard short alias not covered by refuse options) to spawn unbounded worker threads on the receiver (VA:H)."
}
]
},
{
"cvssV3_1": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "HIGH",
"baseScore": 7.5,
"baseSeverity": "HIGH",
"confidentialityImpact": "NONE",
"integrityImpact": "NONE",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"version": "3.1"
},
"format": "CVSS",
"scenarios": [
{
"lang": "en",
"value": "CVSS 3.1 reference score."
}
]
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-770",
"description": "CWE-770 Allocation of Resources Without Limits or Throttling",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-13T14:45:11.164Z",
"orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
"shortName": "VulnCheck"
},
"references": [
{
"name": "GitHub Security Advisory (GHSA-rjvj-qgqg-cvx9)",
"tags": [
"vendor-advisory"
],
"url": "https://github.com/RsyncProject/rsync/security/advisories/GHSA-rjvj-qgqg-cvx9"
},
{
"name": "Release Notes",
"tags": [
"release-notes"
],
"url": "https://github.com/RsyncProject/rsync/releases/tag/v3.5.0"
},
{
"tags": [
"third-party-advisory"
],
"url": "https://www.vulncheck.com/advisories/rsync-dos-via-zt-zstandard-compression-thread-exhaustion"
}
],
"source": {
"discovery": "EXTERNAL"
},
"title": "rsync 3.4.2 \u003c 3.5.0 DoS via --zt Zstandard Compression Thread Exhaustion",
"x_generator": {
"engine": "Vulnogram 1.0.4"
}
}
},
"cveMetadata": {
"assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
"assignerShortName": "VulnCheck",
"cveId": "CVE-2026-70455",
"datePublished": "2026-08-13T14:45:11.164Z",
"dateReserved": "2026-08-04T14:52:23.814Z",
"dateUpdated": "2026-08-13T14:45:11.164Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
}
}
Loading…
Loading…
Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
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.
Loading…
Loading…
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.
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.
Loading…
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.
Loading…