{"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\u00a0--enable-fwd,\u00a0DoChannelOpen()\u00a0in\u00a0src/internal.c\u00a0gates only\u00a0direct-tcpip\u00a0channel opens with the forwarding policy callback.\u00a0forwarded-tcpip\u00a0opens 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\u00a0forwarded-tcpip\u00a0open against the forwards it registered with a\u00a0tcpip-forward\u00a0request, 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"}}}}

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