{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-55851", "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "state": "PUBLISHED", "assignerShortName": "GitHub_M", "dateReserved": "2026-06-17T16:44:40.995Z", "datePublished": "2026-07-21T21:22:34.879Z", "dateUpdated": "2026-07-21T21:22:34.879Z"}, "containers": {"cna": {"title": "Netty codec-haproxy: Signed-Byte Sentinel Collision in HAProxyMessageDecoder Leads to Unbounded Memory Exhaustion", "problemTypes": [{"descriptions": [{"cweId": "CWE-400", "lang": "en", "description": "CWE-400: Uncontrolled Resource Consumption", "type": "CWE"}]}], "metrics": [{"cvssV4_0": {"attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnAvailabilityImpact": "HIGH", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "baseScore": 8.7, "baseSeverity": "HIGH", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N", "version": "4.0"}}], "references": [{"name": "https://github.com/netty/netty/security/advisories/GHSA-q6cq-mhr2-jmr5", "tags": ["x_refsource_CONFIRM"], "url": "https://github.com/netty/netty/security/advisories/GHSA-q6cq-mhr2-jmr5"}, {"name": "https://github.com/netty/netty/commit/5b68c61f37aa4a3045cba624cbea239655c9003b", "tags": ["x_refsource_MISC"], "url": "https://github.com/netty/netty/commit/5b68c61f37aa4a3045cba624cbea239655c9003b"}, {"name": "https://github.com/netty/netty/commit/bb2ff68a1fb71cb4b0eb9a9e17b66c52aff680c6", "tags": ["x_refsource_MISC"], "url": "https://github.com/netty/netty/commit/bb2ff68a1fb71cb4b0eb9a9e17b66c52aff680c6"}, {"name": "https://github.com/netty/netty/releases/tag/netty-4.1.136.Final", "tags": ["x_refsource_MISC"], "url": "https://github.com/netty/netty/releases/tag/netty-4.1.136.Final"}, {"name": "https://github.com/netty/netty/releases/tag/netty-4.2.16.Final", "tags": ["x_refsource_MISC"], "url": "https://github.com/netty/netty/releases/tag/netty-4.2.16.Final"}], "affected": [{"vendor": "netty", "product": "netty", "versions": [{"version": ">= 4.2.0.Final, < 4.2.16.Final", "status": "affected"}, {"version": ">= 4.1.0.Final, < 4.1.136.Final", "status": "affected"}]}], "providerMetadata": {"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "shortName": "GitHub_M", "dateUpdated": "2026-07-21T21:22:34.879Z"}, "descriptions": [{"lang": "en", "value": "Netty is a network application framework for development of protocol servers and clients. In versions 4.2.0.Final up to (but not including) 4.2.16.Final, and 4.1.0.Final up to (but not including) 4.1.135, the `HAProxyMessageDecoder` in Netty's `codec-haproxy` module performs protocol version detection by reading the 13th byte as a signed Java `byte` and widening it to `int` without masking; a PROXY protocol v2 binary prefix followed by version byte `0xFF` sign-extends to `-1`, collides with the decoder's need-more-data sentinel, and causes `ByteToMessageDecoder` to accumulate inbound bytes in an unbounded `cumulation` buffer until direct memory is exhausted. This issue is fixed in versions 4.1.136.Final and 4.2.16.Final."}], "source": {"advisory": "GHSA-q6cq-mhr2-jmr5", "discovery": "UNKNOWN"}}}}

{}

{}

{}

{}