CVE-2026-100665

Netty versions from 4.2.11.Final before 4.2.18.Final contain an incomplete hostname verification fix in the QUIC certificate verification path when using a plain X509TrustManager. The BoringSSLCertificateVerifyCallback discards the SSLEngine for plain trust managers, preventing endpoint identification from running even when HTTPS verification is configured. Attackers on the network path can present a certificate chain for the wrong hostname that the plain trust manager accepts, bypassing hostname authentication for QUIC clients.

CVSS v3 7.5 HIGH

7.5^/10

CVSS v3 : HIGH

Vector :

Exploitability : 3.9 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact NONE

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://github.com/netty/netty/commit/09e72c4fd8007277121ed48db63a124b112b96fe
https://github.com/netty/netty/commit/994e887ed9
https://github.com/netty/netty/security/advisories/GHSA-mj35-3qqm-q387
https://www.vulncheck.com/advisories/netty-4.2.11-through-4.2.17-quic-hostname-verification-bypass
https://github.com/netty/netty/security/advisories/GHSA-mj35-3qqm-q387

Configurations

No configuration.

History

02 Oct 2026, 16:16

Type	Values Removed	Values Added
References	~~() https://github.com/netty/netty/security/advisories/GHSA-mj35-3qqm-q387 -~~	() https://github.com/netty/netty/security/advisories/GHSA-mj35-3qqm-q387 -

26 Sep 2026, 14:16

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-09-26 14:16

Updated : 2026-10-02 16:16

NVD link : CVE-2026-100665

Mitre link : CVE-2026-100665

CVE.ORG link : CVE-2026-100665

JSON object : View

Products Affected

No product.

CWE

CWE-295

Improper Certificate Validation

{"id": "CVE-2026-100665", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-100665", "role": "CISA Coordinator", "options": [{"exploitation": "poc"}, {"automatable": "yes"}, {"technicalImpact": "partial"}], "version": "2.0.3", "timestamp": "2026-10-02T15:46:31.371553Z"}}], "cvssMetricV31": [{"type": "Secondary", "source": "disclosure@vulncheck.com", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 7.5, "attackVector": "NETWORK", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "NONE", "privilegesRequired": "NONE", "confidentialityImpact": "HIGH"}, "impactScore": 3.6, "exploitabilityScore": 3.9}], "cvssMetricV40": [{"type": "Secondary", "source": "disclosure@vulncheck.com", "cvssData": {"Safety": "NOT_DEFINED", "version": "4.0", "Recovery": "NOT_DEFINED", "baseScore": 8.7, "Automatable": "NOT_DEFINED", "attackVector": "NETWORK", "baseSeverity": "HIGH", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/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", "exploitMaturity": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED", "userInteraction": "NONE", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "subIntegrityImpact": "NONE", "vulnIntegrityImpact": "NONE", "integrityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "vulnAvailabilityImpact": "NONE", "availabilityRequirement": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "subConfidentialityImpact": "NONE", "vulnConfidentialityImpact": "HIGH", "confidentialityRequirement": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED"}}]}, "affected": [{"source": "disclosure@vulncheck.com", "affectedData": [{"vendor": "netty", "product": "netty", "versions": [{"status": "affected", "version": "4.2.11.Final", "lessThan": "4.2.18.Final", "versionType": "custom"}, {"status": "unaffected", "version": "4.2.18.Final", "versionType": "custom"}], "packageURL": "pkg:maven/io.netty/netty-codec-classes-quic", "defaultStatus": "unaffected"}]}], "published": "2026-09-26T14:16:49.677", "references": [{"url": "https://github.com/netty/netty/commit/09e72c4fd8007277121ed48db63a124b112b96fe", "source": "disclosure@vulncheck.com"}, {"url": "https://github.com/netty/netty/commit/994e887ed9", "source": "disclosure@vulncheck.com"}, {"url": "https://github.com/netty/netty/security/advisories/GHSA-mj35-3qqm-q387", "source": "disclosure@vulncheck.com"}, {"url": "https://www.vulncheck.com/advisories/netty-4.2.11-through-4.2.17-quic-hostname-verification-bypass", "source": "disclosure@vulncheck.com"}, {"url": "https://github.com/netty/netty/security/advisories/GHSA-mj35-3qqm-q387", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"}], "vulnStatus": "Deferred", "weaknesses": [{"type": "Secondary", "source": "disclosure@vulncheck.com", "description": [{"lang": "en", "value": "CWE-295"}]}], "descriptions": [{"lang": "en", "value": "Netty versions from 4.2.11.Final before 4.2.18.Final contain an incomplete hostname verification fix in the QUIC certificate verification path when using a plain X509TrustManager. The BoringSSLCertificateVerifyCallback discards the SSLEngine for plain trust managers, preventing endpoint identification from running even when HTTPS verification is configured. Attackers on the network path can present a certificate chain for the wrong hostname that the plain trust manager accepts, bypassing hostname authentication for QUIC clients."}], "lastModified": "2026-10-02T16:16:41.803", "sourceIdentifier": "disclosure@vulncheck.com"}