Medium 6.3Published Oct 7, 2026

CVE-2026-81535wolfSSH SSH client accepts unsolicited forwarded-tcpip channel opens without an authorization check

Updated under an hour ago (2026-10-19 10:23 UTC)

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It affects wolfSSL Inc. wolfSSH and 1 other product. Add what you run to find out whether that includes you.

EPSS puts the chance of exploitation in the next 30 days at 0.27%, higher than 18% of scored CVEs.

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Exploited in the last 30 days

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.

CVSS: 6.3 MEDIUM (v4.0, CNA)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
Weakness (CWE): CWE-862, CWE-863
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): 0.27% (percentile 18)
Assigned by: wolfSSL
NVD analysis: Analyzed
Record last updated: Oct 7, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

wolfSSL Inc. wolfSSH wolfssl:wolfssh (from the name)	from 1.4.8 through 1.5.0; fixed at 1.6.0	CNA record
wolfssh wolfssh wolfssh:wolfssh	before 1.6.0	NVD

References

https://github.com/wolfSSL/wolfssh/commit/616eb681e70759c30c3ba158f2b18d7bd954def8patch
https://github.com/wolfSSL/wolfssh/commit/e396a0a4b6b367f10270287446a4be0071742b5cpatch
https://github.com/wolfSSL/wolfssh/commit/79a7f299337a28aa561409688a268d0efe6e295cpatch

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.