CVE-2026-32853

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Attackers can exploit improper bounds checking in the HandleUltraZipBPP() function by manipulating subrectangle header counts to read beyond the allocated heap buffer."}, {"lang": "es", "value": "Las versiones 0.9.15 y anteriores de LibVNCServer (corregido en el commit 009008e) contienen una vulnerabilidad de lectura fuera de l\u00edmites de la pila en el gestor de codificaci\u00f3n UltraZip que permite a un servidor VNC malicioso causar revelaci\u00f3n de informaci\u00f3n o un fallo de la aplicaci\u00f3n. Los atacantes pueden explotar la comprobaci\u00f3n de l\u00edmites incorrecta en la funci\u00f3n HandleUltraZipBPP() manipulando los recuentos de encabezados de subrect\u00e1ngulos para leer m\u00e1s all\u00e1 del b\u00fafer de pila asignado."}], "id": "CVE-2026-32853", "lastModified": "2026-07-14T19:16:57.773", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 8.1, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 2.8, "impactScore": 5.2, "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": "NONE", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:L/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": "LOW", "vulnConfidentialityImpact": "LOW", "vulnIntegrityImpact": "NONE", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "source": "disclosure@vulncheck.com", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-32853", "options": [{"exploitation": "poc"}, {"automatable": "yes"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-03-25T13:41:12.751342Z", "version": "2.0.3"}}]}, "published": "2026-03-24T18:16:09.253", "references": [{"source": "disclosure@vulncheck.com", "tags": ["Patch"], "url": "https://github.com/LibVNC/libvncserver/commit/009008e2f4d5a54dd71f422070df3af7b3dbc931"}, {"source": "disclosure@vulncheck.com", "tags": ["Vendor Advisory"], "url": "https://github.com/LibVNC/libvncserver/security/advisories/GHSA-87q7-v983-qwcj"}, {"source": "disclosure@vulncheck.com", "tags": ["Exploit", "Vendor Advisory"], "url": "https://www.vulncheck.com/advisories/libvncserver-ultrazip-encoding-heap-out-of-bounds-read"}, {"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["Vendor Advisory"], "url": "https://github.com/LibVNC/libvncserver/security/advisories/GHSA-87q7-v983-qwcj"}], "sourceIdentifier": "disclosure@vulncheck.com", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-125"}], "source": "disclosure@vulncheck.com", "type": "Secondary"}]}

{"bugzilla": {"description": "LibVNCServer: LibVNCServer: Information disclosure or Denial of Service via heap out-of-bounds read in UltraZip encoding", "id": "2450843", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2450843"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.4", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:L", "status": "draft"}, "cwe": "CWE-125", "details": ["A flaw was found in LibVNCServer. A malicious VNC server can exploit an improper bounds checking vulnerability in the UltraZip encoding handler, specifically within the `HandleUltraZipBPP()` function. By manipulating subrectangle header counts, an attacker can read beyond the allocated memory buffer. This heap out-of-bounds read can lead to information disclosure or cause the application to crash, resulting in a Denial of Service (DoS)."], "mitigation": {"lang": "en:us", "value": "Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability."}, "name": "CVE-2026-32853", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Fix deferred", "package_name": "libvncserver", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Fix deferred", "package_name": "libvncserver", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Fix deferred", "package_name": "libvncserver", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "gnome-remote-desktop", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2026-03-24T17:30:40Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-32853\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-32853\nhttps://github.com/LibVNC/libvncserver/commit/009008e2f4d5a54dd71f422070df3af7b3dbc931\nhttps://github.com/LibVNC/libvncserver/security/advisories/GHSA-87q7-v983-qwcj\nhttps://www.vulncheck.com/advisories/libvncserver-ultrazip-encoding-heap-out-of-bounds-read"], "threat_severity": "Moderate"}

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