CVE-2026-32853 (GCVE-0-2026-32853)
Vulnerability from cvelistv5 – Published: 2026-03-24 17:30 – Updated: 2026-07-14 18:40
VLAI
EPSS
VEX
Title
LibVNCServer UltraZip Encoding Heap Out-of-bounds Read
Summary
LibVNCServer versions 0.9.15 and prior (fixed in commit 009008e) contain a heap out-of-bounds read vulnerability in the UltraZip encoding handler that allows a malicious VNC server to cause information disclosure or application crash. Attackers can exploit improper bounds checking in the HandleUltraZipBPP() function by manipulating subrectangle header counts to read beyond the allocated heap buffer.
Severity
SSVC
Exploitation: poc
Automatable: yes
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-03-25 13:41 UTC
CWE
- CWE-125 - Out-of-bounds read
Assigner
References
3 references
| URL | Tags |
|---|---|
| https://github.com/LibVNC/libvncserver/security/a… | vendor-advisory |
| https://github.com/LibVNC/libvncserver/commit/009… | patch |
| https://www.vulncheck.com/advisories/libvncserver… | third-party-advisory |
Impacted products
1 product
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| LibVNC | LibVNCServer |
Affected:
0 , ≤ 0.9.15
(semver)
Unaffected: 009008e2f4d5a54dd71f422070df3af7b3dbc931 (git) cpe:2.3:a:libvnc_project:libvncserver:*:*:*:*:*:*:*:* |
{
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-32853",
"options": [
{
"Exploitation": "poc"
},
{
"Automatable": "yes"
},
{
"Technical Impact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-03-25T13:41:12.751342Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-03-25T13:41:15.171Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"references": [
{
"tags": [
"exploit"
],
"url": "https://github.com/LibVNC/libvncserver/security/advisories/GHSA-87q7-v983-qwcj"
}
],
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"packageURL": "pkg:github/LibVNC/libvncserver",
"product": "LibVNCServer",
"repo": "https://github.com/LibVNC/libvncserver",
"vendor": "LibVNC",
"versions": [
{
"lessThanOrEqual": "0.9.15",
"status": "affected",
"version": "0",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "009008e2f4d5a54dd71f422070df3af7b3dbc931",
"versionType": "git"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:a:libvnc_project:libvncserver:*:*:*:*:*:*:*:*",
"versionEndIncluding": "0.9.15",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"credits": [
{
"lang": "en",
"type": "finder",
"value": "Kazuma Matsumoto, a security researcher at GMO Cybersecurity by IERAE, Inc."
}
],
"descriptions": [
{
"lang": "en",
"supportingMedia": [
{
"base64": false,
"type": "text/html",
"value": "LibVNCServer versions 0.9.15 and prior (fixed in\u0026nbsp;commit 009008e) contain a heap out-of-bounds read vulnerability in the UltraZip encoding handler that allows a malicious VNC server to cause information disclosure or application crash. Attackers can exploit improper bounds checking in the HandleUltraZipBPP() function by manipulating subrectangle header counts to read beyond the allocated heap buffer.\u003cbr\u003e"
}
],
"value": "LibVNCServer versions 0.9.15 and prior (fixed in\u00a0commit 009008e) contain a heap out-of-bounds read vulnerability in the UltraZip encoding handler that allows a malicious VNC server to cause information disclosure or application crash. Attackers can exploit improper bounds checking in the HandleUltraZipBPP() function by manipulating subrectangle header counts to read beyond the allocated heap buffer."
}
],
"metrics": [
{
"cvssV4_0": {
"Automatable": "NOT_DEFINED",
"Recovery": "NOT_DEFINED",
"Safety": "NOT_DEFINED",
"attackComplexity": "LOW",
"attackRequirements": "NONE",
"attackVector": "NETWORK",
"baseScore": 6.9,
"baseSeverity": "MEDIUM",
"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:L/VI:N/VA:L/SC:N/SI:N/SA:N",
"version": "4.0",
"vulnAvailabilityImpact": "LOW",
"vulnConfidentialityImpact": "LOW",
"vulnIntegrityImpact": "NONE",
"vulnerabilityResponseEffort": "NOT_DEFINED"
},
"format": "CVSS",
"scenarios": [
{
"lang": "en",
"value": "GENERAL"
}
]
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-125",
"description": "CWE-125 Out-of-bounds read",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-07-14T18:40:05.005Z",
"orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
"shortName": "VulnCheck"
},
"references": [
{
"tags": [
"vendor-advisory"
],
"url": "https://github.com/LibVNC/libvncserver/security/advisories/GHSA-87q7-v983-qwcj"
},
{
"tags": [
"patch"
],
"url": "https://github.com/LibVNC/libvncserver/commit/009008e2f4d5a54dd71f422070df3af7b3dbc931"
},
{
"tags": [
"third-party-advisory"
],
"url": "https://www.vulncheck.com/advisories/libvncserver-ultrazip-encoding-heap-out-of-bounds-read"
}
],
"source": {
"discovery": "EXTERNAL"
},
"title": "LibVNCServer UltraZip Encoding Heap Out-of-bounds Read",
"x_generator": {
"engine": "Vulnogram 1.0.1"
}
}
},
"cveMetadata": {
"assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
"assignerShortName": "VulnCheck",
"cveId": "CVE-2026-32853",
"datePublished": "2026-03-24T17:30:40.061Z",
"dateReserved": "2026-03-16T18:11:41.759Z",
"dateUpdated": "2026-07-14T18:40:05.005Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"epss": {
"cve": "CVE-2026-32853",
"date": "2026-09-22",
"epss": "0.00437",
"percentile": "0.37466"
},
"nvd": {
"cve": {
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"packageURL": "pkg:github/LibVNC/libvncserver",
"product": "LibVNCServer",
"repo": "https://github.com/LibVNC/libvncserver",
"vendor": "LibVNC",
"versions": [
{
"lessThanOrEqual": "0.9.15",
"status": "affected",
"version": "0",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "009008e2f4d5a54dd71f422070df3af7b3dbc931",
"versionType": "git"
}
]
}
],
"source": "disclosure@vulncheck.com"
}
],
"configurations": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:a:libvncserver_project:libvncserver:*:*:*:*:*:*:*:*",
"matchCriteriaId": "A73C0099-80A6-4B55-8B34-7968BFADE90A",
"versionEndExcluding": "0.9.15",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "LibVNCServer versions 0.9.15 and prior (fixed in\u00a0commit 009008e) contain a heap out-of-bounds read vulnerability in the UltraZip encoding handler that allows a malicious VNC server to cause information disclosure or application crash. 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"
}
]
}
},
"redhat_vex": {
"aggregate_severity": "Moderate",
"current_release_date": "2026-06-28T07:29:29+00:00",
"cve": "CVE-2026-32853",
"id": "CVE-2026-32853",
"initial_release_date": "2026-03-24T17:30:40.061000+00:00",
"product_status:known_affected": "8",
"product_status:known_not_affected": "3",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "LibVNCServer: LibVNCServer: Information disclosure or Denial of Service via heap out-of-bounds read in UltraZip encoding",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-32853.json",
"version": "3"
},
"suse_vex": {
"aggregate_severity": "important",
"current_release_date": "2026-07-15T05:19:25Z",
"cve": "CVE-2026-32853",
"id": "CVE-2026-32853",
"initial_release_date": "2026-03-25T16:53:29Z",
"product_status:known_affected": "12",
"product_status:recommended": "33",
"source": "SUSE CSAF VEX",
"status": "interim",
"title": "SUSE CVE CVE-2026-32853",
"url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-32853.json",
"version": "11"
},
"vulnrichment": {
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-32853",
"options": [
{
"Exploitation": "poc"
},
{
"Automatable": "yes"
},
{
"Technical Impact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-03-25T13:41:12.751342Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-03-25T13:41:06.842Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"references": [
{
"tags": [
"exploit"
],
"url": "https://github.com/LibVNC/libvncserver/security/advisories/GHSA-87q7-v983-qwcj"
}
],
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "LibVNCServer",
"repo": "https://github.com/LibVNC/libvncserver",
"vendor": "LibVNC",
"versions": [
{
"lessThanOrEqual": "0.9.15",
"status": "affected",
"version": "0",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "009008e2f4d5a54dd71f422070df3af7b3dbc931",
"versionType": "git"
}
]
}
],
"credits": [
{
"lang": "en",
"type": "finder",
"value": "Kazuma Matsumoto, a security researcher at GMO Cybersecurity by IERAE, Inc."
}
],
"descriptions": [
{
"lang": "en",
"supportingMedia": [
{
"base64": false,
"type": "text/html",
"value": "LibVNCServer versions 0.9.15 and prior (fixed in\u0026nbsp;commit 009008e) contain a heap out-of-bounds read vulnerability in the UltraZip encoding handler that allows a malicious VNC server to cause information disclosure or application crash. Attackers can exploit improper bounds checking in the HandleUltraZipBPP() function by manipulating subrectangle header counts to read beyond the allocated heap buffer.\u003cbr\u003e"
}
],
"value": "LibVNCServer versions 0.9.15 and prior (fixed in\u00a0commit 009008e) contain a heap out-of-bounds read vulnerability in the UltraZip encoding handler that allows a malicious VNC server to cause information disclosure or application crash. Attackers can exploit improper bounds checking in the HandleUltraZipBPP() function by manipulating subrectangle header counts to read beyond the allocated heap buffer."
}
],
"metrics": [
{
"cvssV4_0": {
"Automatable": "NOT_DEFINED",
"Recovery": "NOT_DEFINED",
"Safety": "NOT_DEFINED",
"attackComplexity": "LOW",
"attackRequirements": "NONE",
"attackVector": "NETWORK",
"baseScore": 6.9,
"baseSeverity": "MEDIUM",
"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:L/VI:N/VA:L/SC:N/SI:N/SA:N",
"version": "4.0",
"vulnAvailabilityImpact": "LOW",
"vulnConfidentialityImpact": "LOW",
"vulnIntegrityImpact": "NONE",
"vulnerabilityResponseEffort": "NOT_DEFINED"
},
"format": "CVSS",
"scenarios": [
{
"lang": "en",
"value": "GENERAL"
}
]
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-125",
"description": "CWE-125 Out-of-bounds read",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-03-24T17:30:48.607Z",
"orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
"shortName": "VulnCheck"
},
"references": [
{
"tags": [
"vendor-advisory"
],
"url": "https://github.com/LibVNC/libvncserver/security/advisories/GHSA-87q7-v983-qwcj"
},
{
"tags": [
"patch"
],
"url": "https://github.com/LibVNC/libvncserver/commit/009008e2f4d5a54dd71f422070df3af7b3dbc931"
},
{
"tags": [
"third-party-advisory"
],
"url": "https://www.vulncheck.com/advisories/libvncserver-ultrazip-encoding-heap-out-of-bounds-read"
}
],
"source": {
"discovery": "EXTERNAL"
},
"title": "LibVNCServer UltraZip Encoding Heap Out-of-bounds Read",
"x_generator": {
"engine": "Vulnogram 1.0.1"
}
}
},
"cveMetadata": {
"assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
"assignerShortName": "VulnCheck",
"cveId": "CVE-2026-32853",
"datePublished": "2026-03-24T17:30:40.061Z",
"dateReserved": "2026-03-16T18:11:41.759Z",
"dateUpdated": "2026-03-24T17:30:48.607Z",
"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…