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CVE-2026-81535

9.1, critical

wolfSSL Inc. wolfSSH Missing Authorization Vulnerability

NVD (opens in a new tab) CVE.org (opens in a new tab)
CVSS
9.1, critical critical CVSS v3.1
EPSS, next 30 days
0.3% higher than 17.6% of scored CVEs
Exploitation
No public evidence
Published
7 Oct 202610 days ago

Description

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.

Details

Vendor
wolfSSL Inc.
Product
wolfSSH
Weakness
CWE-862 (opens in a new tab)
Status
Analyzed
Updated
13 Oct 2026
Assigner
facts@wolfssl.com

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

References 3

Patches and fixes 3

The kind is read from NVD's tags where present and from the shape of the URL otherwise, so treat it as a hint.

Other wolfSSL Inc. CVEs

Every wolfSSL Inc. CVE we hold

Same vendor in what we hold, not a known link between the flaws.

  • CVE-2026-16516 wolfSSH does not validate that the ECDSA curve identifier in a KEXDH_REPLY host key blob matches the algorithm negotiated during key… EPSS 0.1% 7.4, high
  • CVE-2026-83742 wolfSSL Inc. wolfSSH Stack-based Buffer Overflow Vulnerability EPSS 0.4% 8.8, high

Beyond this page

Is CVE-2026-81535 in your network?

This page tells you how dangerous CVE-2026-81535 is out there. Whether it sits on one of your devices, only a scan of your own network can tell. That is what our systems do, every day, for the companies we protect.

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Check your exposure

Assembled from the NVD 2.0 API, the CISA Known Exploited Vulnerabilities Catalog and FIRST EPSS. Scores are as of our last collection on 17 Oct 2026, not the live upstream state.