CVE-2026-43620

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Attackers can exploit the vulnerability by setting CF_INC_RECURSE in compatibility flags and sending a specially crafted file list where the first sorted entry is not the leading dot directory, followed by a transfer record with ndx=0 and an iflag word without ITEM_TRANSFER, causing the receiver to read 8 bytes before the allocated pointer array and dereference an invalid pointer at an unmapped address, resulting in a deterministic SIGSEGV crash of the rsync client."}, {"lang": "es", "value": "La versi\u00f3n 3.4.2 de Rsync y anteriores contienen una vulnerabilidad de lectura de array fuera de l\u00edmites en el lado del receptor en recv_files() en receiver.c que permite a un servidor rsync malicioso bloquear el proceso del cliente rsync. Los atacantes pueden explotar la vulnerabilidad al establecer CF_INC_RECURSE en los indicadores de compatibilidad y enviar una lista de archivos especialmente dise\u00f1ada donde la primera entrada ordenada no es el directorio de punto inicial, seguido de un registro de transferencia con ndx=0 y una palabra iflag sin ITEM_TRANSFER, lo que hace que el receptor lea 8 bytes antes del array de punteros asignado y desreferencie un puntero inv\u00e1lido en una direcci\u00f3n no mapeada, lo que resulta en un bloqueo SIGSEGV determinista del cliente rsync."}], "id": "CVE-2026-43620", "lastModified": "2026-07-24T09:10:00.153", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 6.5, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 2.8, "impactScore": 3.6, "source": "disclosure@vulncheck.com", "type": "Secondary"}, {"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 5.5, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 3.6, "source": "nvd@nist.gov", "type": "Primary"}], "cvssMetricV40": [{"cvssData": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "NONE", "attackVector": "NETWORK", "availabilityRequirement": "NOT_DEFINED", "baseScore": 6.9, "baseSeverity": "MEDIUM", "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": "ACTIVE", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/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-2026-43620", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-05-20T14:11:42.448773Z", "version": "2.0.3"}}]}, "published": "2026-05-20T02:16:36.727", "references": [{"source": "disclosure@vulncheck.com", "tags": ["Release Notes"], "url": "https://github.com/RsyncProject/rsync/releases/tag/v3.4.3"}, {"source": "disclosure@vulncheck.com", "tags": ["Vendor Advisory"], "url": "https://github.com/RsyncProject/rsync/security/advisories/GHSA-28pw-r563-rxvm"}, {"source": "disclosure@vulncheck.com", "tags": ["Third Party Advisory"], "url": "https://www.vulncheck.com/advisories/rsync-out-of-bounds-array-read-via-recv-files"}], "sourceIdentifier": "disclosure@vulncheck.com", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-125"}], "source": "disclosure@vulncheck.com", "type": "Secondary"}]}

{"bugzilla": {"description": "rsync: rsync: Remote Denial of Service via Out-of-bounds Read", "id": "2469057", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2469057"}, "csaw": false, "cvss3": {"cvss3_base_score": "6.5", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-125", "details": ["A flaw was found in rsync. A malicious rsync server can exploit an out-of-bounds read vulnerability in the `recv_files()` function. By manipulating compatibility flags and transfer records, the server can cause a connecting client to attempt to read memory outside of allocated bounds. This can lead to a segmentation fault, resulting in a denial of service for the client."], "mitigation": {"lang": "en:us", "value": "To mitigate this issue, rsync clients can be configured to disable incremental recursion when pulling from untrusted sources. This can be achieved by using the `--no-inc-recursive` option.\nExample:\n`rsync --no-inc-recursive [OPTIONS] SOURCE DESTINATION`\nDisabling incremental recursion may affect the efficiency of transfers for large, frequently updated directories."}, "name": "CVE-2026-43620", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Fix deferred", "package_name": "rsync", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Fix deferred", "package_name": "rsync", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Fix deferred", "package_name": "rsync", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Fix deferred", "package_name": "rsync", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "rsync", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/a:redhat:openshift:4", "fix_state": "Fix deferred", "package_name": "rhcos", "product_name": "Red Hat OpenShift Container Platform 4"}], "public_date": "2026-05-20T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-43620\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-43620"], "statement": "This Moderate impact flaw in rsync clients allows a remote, unauthenticated attacker to cause a denial-of-service by crafting a malicious rsync server. When a client pulls from such a server, an out-of-bounds read occurs due to an incomplete fix, leading to a deterministic crash. This affects any rsync client performing a normal pull from an attacker-controlled URL, as the `inc_recurse` option, which is enabled by default, facilitates the exploit.", "threat_severity": "Moderate"}

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