{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-81535",
        "assignerOrgId": "50d2cd11-d01a-48ed-9441-5bfce9d63b27",
        "state": "PUBLISHED",
        "assignerShortName": "wolfSSL",
        "dateReserved": "2026-08-26T23:09:37.634Z",
        "datePublished": "2026-10-07T02:39:27.830Z",
        "dateUpdated": "2026-10-07T02:39:27.830Z"
    },
    "containers": {
        "cna": {
            "providerMetadata": {
                "orgId": "50d2cd11-d01a-48ed-9441-5bfce9d63b27",
                "shortName": "wolfSSL",
                "dateUpdated": "2026-10-07T02:39:27.830Z"
            },
            "title": "wolfSSH SSH client accepts unsolicited forwarded-tcpip channel opens without an authorization check",
            "problemTypes": [
                {
                    "descriptions": [
                        {
                            "lang": "en",
                            "cweId": "CWE-862",
                            "description": "CWE-862 Missing Authorization",
                            "type": "CWE"
                        }
                    ]
                },
                {
                    "descriptions": [
                        {
                            "lang": "en",
                            "cweId": "CWE-863",
                            "description": "CWE-863 Incorrect Authorization",
                            "type": "CWE"
                        }
                    ]
                }
            ],
            "impacts": [
                {
                    "capecId": "CAPEC-130",
                    "descriptions": [
                        {
                            "lang": "en",
                            "value": "CAPEC-130 Excessive Allocation"
                        }
                    ]
                }
            ],
            "affected": [
                {
                    "vendor": "wolfSSL Inc.",
                    "product": "wolfSSH",
                    "repo": "https://github.com/wolfSSL/wolfssh",
                    "modules": [
                        "forwarding"
                    ],
                    "programFiles": [
                        "src/internal.c"
                    ],
                    "versions": [
                        {
                            "status": "affected",
                            "version": "1.4.8",
                            "lessThanOrEqual": "1.5.0",
                            "changes": [
                                {
                                    "at": "1.6.0",
                                    "status": "unaffected"
                                }
                            ],
                            "versionType": "semver"
                        }
                    ],
                    "defaultStatus": "unaffected"
                }
            ],
            "descriptions": [
                {
                    "lang": "en",
                    "value": "In wolfSSH through 1.5.0 built with --enable-fwd, DoChannelOpen() in src/internal.c gates only direct-tcpip channel opens with the forwarding policy callback. forwarded-tcpip opens are admitted without an authorization check and are not capped in number, allowing a malicious SSH peer to make an endpoint allocate unbounded per-channel buffers for forwarding channels the application never authorized. A client also does not check a forwarded-tcpip open against the forwards it registered with a tcpip-forward request, as RFC 4254 section 7.2 requires, so a malicious server can open forwarding channels for addresses and ports the client never asked it to forward.",
                    "supportingMedia": [
                        {
                            "type": "text/html",
                            "base64": false,
                            "value": "In wolfSSH through 1.5.0 built with&nbsp;<code>--enable-fwd</code>,&nbsp;<code>DoChannelOpen()</code>&nbsp;in&nbsp;<code>src/internal.c</code>&nbsp;gates only&nbsp;<code>direct-tcpip</code>&nbsp;channel opens with the forwarding policy callback.&nbsp;<code>forwarded-tcpip</code>&nbsp;opens are admitted without an authorization check and are not capped in number, allowing a malicious SSH peer to make an endpoint allocate unbounded per-channel buffers for forwarding channels the application never authorized. A client also does not check a&nbsp;<code>forwarded-tcpip</code>&nbsp;open against the forwards it registered with a&nbsp;<code>tcpip-forward</code>&nbsp;request, as RFC 4254 section 7.2 requires, so a malicious server can open forwarding channels for addresses and ports the client never asked it to forward.<br>"
                        }
                    ]
                }
            ],
            "references": [
                {
                    "url": "https://github.com/wolfSSL/wolfssh/commit/616eb681e70759c30c3ba158f2b18d7bd954def8",
                    "tags": [
                        "patch"
                    ]
                },
                {
                    "url": "https://github.com/wolfSSL/wolfssh/commit/e396a0a4b6b367f10270287446a4be0071742b5c",
                    "name": "Fix commit e396a0a4 (match forwarded-tcpip opens to registered forwards, PR #1148)",
                    "tags": [
                        "patch"
                    ]
                },
                {
                    "url": "https://github.com/wolfSSL/wolfssh/commit/79a7f299337a28aa561409688a268d0efe6e295c",
                    "name": "Fix commit 79a7f299 (match forwarded-tcpip on every client session, PR #1220)",
                    "tags": [
                        "patch"
                    ]
                }
            ],
            "metrics": [
                {
                    "format": "CVSS",
                    "scenarios": [
                        {
                            "lang": "en",
                            "value": "GENERAL"
                        }
                    ],
                    "cvssV4_0": {
                        "attackVector": "NETWORK",
                        "attackComplexity": "LOW",
                        "attackRequirements": "PRESENT",
                        "privilegesRequired": "NONE",
                        "userInteraction": "NONE",
                        "vulnConfidentialityImpact": "NONE",
                        "subConfidentialityImpact": "NONE",
                        "vulnIntegrityImpact": "NONE",
                        "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": 6.3,
                        "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N"
                    }
                }
            ],
            "credits": [
                {
                    "lang": "en",
                    "value": "zhangph (GitHub afldl)",
                    "type": "finder"
                }
            ],
            "source": {
                "discovery": "EXTERNAL"
            },
            "x_generator": {
                "engine": "Vulnogram 1.0.5"
            }
        }
    }
}