{"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":"2026-10-07T18:37:36.186Z"},"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"}},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-10-07T18:37:10.078645Z","id":"CVE-2026-81535","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-10-07T18:37:36.186Z"}}]}}