{"dataType": "CVE_RECORD", "cveMetadata": {"cveId": "CVE-2026-40395", "assignerOrgId": "8254265b-2729-46b6-b9e3-3dfca2d5bfca", "state": "PUBLISHED", "assignerShortName": "mitre", "dateReserved": "2026-04-12T19:21:08.847Z", "datePublished": "2026-04-12T19:21:09.265Z", "dateUpdated": "2026-04-12T19:33:44.790Z"}, "containers": {"cna": {"affected": [{"defaultStatus": "unaffected", "product": "Varnish Enterprise", "vendor": "varnish-software", "versions": [{"lessThan": "6.0.16r12", "status": "affected", "version": "6.0.9r5", "versionType": "custom"}]}], "descriptions": [{"lang": "en", "value": "Varnish Enterprise before 6.0.16r12 allows a \"workspace overflow\" denial of service (daemon panic) for shared VCL. The headerplus.write_req0() function from vmod_headerplus updates the underlying req0, which is normally the original read-only request from which req is derived (readable and writable from VCL). This is useful in the active VCL, after amending req, to prepare a refined req0 before switching to a different VCL with the return (vcl(<label>)) action. This is for example how the Varnish Controller operates shared VCL deployments. If the amended req contained too many header fields for req0, this would have resulted in a workspace overflow that would in turn trigger a panic and crash the Varnish Enterprise server. This could be used as a Denial of Service attack vector by malicious clients."}], "metrics": [{"cvssV3_1": {"attackComplexity": "HIGH", "attackVector": "NETWORK", "availabilityImpact": "LOW", "baseScore": 4, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "CHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:L", "version": "3.1"}, "format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}]}], "problemTypes": [{"descriptions": [{"cweId": "CWE-770", "description": "CWE-770 Allocation of Resources Without Limits or Throttling", "lang": "en", "type": "CWE"}]}], "providerMetadata": {"orgId": "8254265b-2729-46b6-b9e3-3dfca2d5bfca", "shortName": "mitre", "dateUpdated": "2026-04-12T19:33:44.790Z"}, "references": [{"url": "https://docs.varnish-software.com/security/VEV00003/"}], "x_generator": {"engine": "CVE-Request-form 0.0.1"}, "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:varnish-software:varnish_enterprise:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.0.9r5", "versionEndExcluding": "6.0.16r12"}]}]}]}}, "dataVersion": "5.2"}

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{"cveTags": [], "descriptions": [{"lang": "en", "value": "Varnish Enterprise before 6.0.16r12 allows a \"workspace overflow\" denial of service (daemon panic) for shared VCL. The headerplus.write_req0() function from vmod_headerplus updates the underlying req0, which is normally the original read-only request from which req is derived (readable and writable from VCL). This is useful in the active VCL, after amending req, to prepare a refined req0 before switching to a different VCL with the return (vcl(<label>)) action. This is for example how the Varnish Controller operates shared VCL deployments. If the amended req contained too many header fields for req0, this would have resulted in a workspace overflow that would in turn trigger a panic and crash the Varnish Enterprise server. This could be used as a Denial of Service attack vector by malicious clients."}], "id": "CVE-2026-40395", "lastModified": "2026-04-12T20:16:18.893", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "HIGH", "attackVector": "NETWORK", "availabilityImpact": "LOW", "baseScore": 4.0, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "CHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:L", "version": "3.1"}, "exploitabilityScore": 2.2, "impactScore": 1.4, "source": "cve@mitre.org", "type": "Secondary"}]}, "published": "2026-04-12T20:16:18.893", "references": [{"source": "cve@mitre.org", "url": "https://docs.varnish-software.com/security/VEV00003/"}], "sourceIdentifier": "cve@mitre.org", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-770"}], "source": "cve@mitre.org", "type": "Primary"}]}

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