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    "cveMetadata": {
        "cveId": "CVE-2026-5503",
        "assignerOrgId": "50d2cd11-d01a-48ed-9441-5bfce9d63b27",
        "state": "PUBLISHED",
        "assignerShortName": "wolfSSL",
        "dateReserved": "2026-04-03T15:55:20.740Z",
        "datePublished": "2026-04-09T22:35:39.437Z",
        "dateUpdated": "2026-04-10T17:58:51.312Z"
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    "containers": {
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                "dateUpdated": "2026-04-09T22:35:39.437Z"
            },
            "title": "out-of-bounds write in TLSX_EchChangeSNI via attacker-controlled publicName",
            "problemTypes": [
                {
                    "descriptions": [
                        {
                            "lang": "en",
                            "cweId": "CWE-787",
                            "description": "CWE-787 Out-of-bounds write",
                            "type": "CWE"
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                    ]
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            "affected": [
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                    "vendor": "wolfSSL",
                    "product": "wolfSSL",
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                            "version": "0",
                            "lessThanOrEqual": "5.9.0",
                            "versionType": "semver"
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            "descriptions": [
                {
                    "lang": "en",
                    "value": "In TLSX_EchChangeSNI, the ctx->extensions branch set extensions unconditionally even when TLSX_Find returned NULL. This caused TLSX_UseSNI to attach the attacker-controlled publicName to the shared WOLFSSL_CTX when no inner SNI was configured. TLSX_EchRestoreSNI then failed to clean it up because its removal was gated on serverNameX != NULL. The inner ClientHello was sized before the pollution but written after it, causing TLSX_SNI_Write to memcpy 255 bytes past the allocation boundary.",
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                            "value": "In TLSX_EchChangeSNI, the ctx->extensions branch set extensions unconditionally even when TLSX_Find returned NULL. This caused TLSX_UseSNI to attach the attacker-controlled publicName to the shared WOLFSSL_CTX when no inner SNI was configured. TLSX_EchRestoreSNI then failed to clean it up because its removal was gated on serverNameX != NULL. The inner ClientHello was sized before the pollution but written after it, causing TLSX_SNI_Write to memcpy 255 bytes past the allocation boundary."
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            "references": [
                {
                    "url": "https://github.com/wolfSSL/wolfssl/pull/10102"
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                        "attackVector": "NETWORK",
                        "attackComplexity": "LOW",
                        "attackRequirements": "NONE",
                        "privilegesRequired": "NONE",
                        "userInteraction": "NONE",
                        "vulnConfidentialityImpact": "NONE",
                        "subConfidentialityImpact": "NONE",
                        "vulnIntegrityImpact": "LOW",
                        "subIntegrityImpact": "NONE",
                        "vulnAvailabilityImpact": "LOW",
                        "subAvailabilityImpact": "NONE",
                        "exploitMaturity": "NOT_DEFINED",
                        "Safety": "NOT_DEFINED",
                        "Automatable": "NOT_DEFINED",
                        "Recovery": "NOT_DEFINED",
                        "valueDensity": "NOT_DEFINED",
                        "vulnerabilityResponseEffort": "NOT_DEFINED",
                        "providerUrgency": "NOT_DEFINED",
                        "version": "4.0",
                        "baseSeverity": "MEDIUM",
                        "baseScore": 6.9,
                        "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N"
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            ],
            "credits": [
                {
                    "lang": "en",
                    "value": "Calif.io in collaboration with Claude and Anthropic Research",
                    "type": "finder"
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            "source": {
                "discovery": "EXTERNAL"
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            {
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                            "content": {
                                "timestamp": "2026-04-10T17:58:43.475862Z",
                                "id": "CVE-2026-5503",
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                                        "Exploitation": "none"
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                "title": "CISA ADP Vulnrichment",
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                    "dateUpdated": "2026-04-10T17:58:51.312Z"
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