{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-61674", "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "state": "PUBLISHED", "assignerShortName": "GitHub_M", "dateReserved": "2026-07-10T18:25:21.468Z", "datePublished": "2026-09-21T16:10:15.276Z", "dateUpdated": "2026-09-21T16:10:15.276Z"}, "containers": {"cna": {"title": "Fluent Bit: Remote stack buffer overflow in Fluent Bit `out_forward` Secure-Forward `PONG` handler", "problemTypes": [{"descriptions": [{"cweId": "CWE-121", "lang": "en", "description": "CWE-121: Stack-based Buffer Overflow", "type": "CWE"}]}, {"descriptions": [{"cweId": "CWE-787", "lang": "en", "description": "CWE-787: Out-of-bounds Write", "type": "CWE"}]}, {"descriptions": [{"cweId": "CWE-843", "lang": "en", "description": "CWE-843: Access of Resource Using Incompatible Type ('Type Confusion')", "type": "CWE"}]}], "metrics": [{"cvssV4_0": {"attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "HIGH", "vulnIntegrityImpact": "HIGH", "vulnAvailabilityImpact": "HIGH", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "baseScore": 9.2, "baseSeverity": "CRITICAL", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N", "version": "4.0"}}], "references": [{"name": "https://github.com/fluent/fluent-bit/security/advisories/GHSA-jrp8-r9hx-gf73", "tags": ["x_refsource_CONFIRM"], "url": "https://github.com/fluent/fluent-bit/security/advisories/GHSA-jrp8-r9hx-gf73"}, {"name": "https://github.com/fluent/fluent-bit/pull/11945", "tags": ["x_refsource_MISC"], "url": "https://github.com/fluent/fluent-bit/pull/11945"}, {"name": "https://github.com/fluent/fluent-bit/commit/45486556be9d023e194665e243f156b228e195e0", "tags": ["x_refsource_MISC"], "url": "https://github.com/fluent/fluent-bit/commit/45486556be9d023e194665e243f156b228e195e0"}, {"name": "https://github.com/fluent/fluent-bit/releases/tag/v5.0.8", "tags": ["x_refsource_MISC"], "url": "https://github.com/fluent/fluent-bit/releases/tag/v5.0.8"}], "affected": [{"vendor": "fluent", "product": "fluent-bit", "versions": [{"version": ">= 0.11.0, < 5.0.8", "status": "affected"}]}], "providerMetadata": {"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "shortName": "GitHub_M", "dateUpdated": "2026-09-21T16:10:15.276Z"}, "descriptions": [{"lang": "en", "value": "Fluent Bit is a fast and lightweight logs, metrics, and traces processor for Linux, BSD, macOS, and Windows. From 0.11.0 until 5.0.8, plugins/out_forward/forward.c secure_forward_pong copies the server-controlled PONG[2] reason into the 32-byte stack buffer msg with memcpy without checking its MessagePack type or length. An attacker who controls or can impersonate an out_forward Secure Forward destination configured with Shared_Key or Empty_Shared_Key can send an oversized reason during the first handshake and overwrite stack control data. Protected builds reliably terminate, while builds without a stack canary or with a disclosure can allow remote code execution as the Fluent Bit process user. When the opt-in --supervisor mode is used, fork-only respawns preserve the canary and address layout, allowing repeated crash-or-survive probes to support code execution on a hardened build; ordinary exec-based or service-manager restarts do not preserve that state. This issue is fixed in version 5.0.8."}], "source": {"advisory": "GHSA-jrp8-r9hx-gf73", "discovery": "UNKNOWN"}}}}

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