CVE-2026-81535Network attack vectorHinoki check available

Memory exhaustion via unchecked forwarding channel opens

Published Oct 7, 2026 · Updated Oct 7, 2026

Improper authorization in wolfSSL wolfSSH 1.4.8 through 1.5.0 allows remote attackers to exhaust memory via forwarded-tcpip channel opens. DoChannelOpen() admits these opens without the forwarding policy callback, while clients fail to match them against registered forwards, allowing unchecked per-channel buffer allocation. Exposure requires a forwarding-enabled build and a malicious SSH peer; the resulting memory pressure can interrupt the endpoint.

CVSS severityUnavailable
Unscored
EPSS probability0.27%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Get started

Summary

What happened

Improper authorization in wolfSSL wolfSSH 1.4.8 through 1.5.0 allows remote attackers to exhaust memory via forwarded-tcpip channel opens. DoChannelOpen() admits these opens without the forwarding policy callback, while clients fail to match them against registered forwards, allowing unchecked per-channel buffer allocation. Exposure requires a forwarding-enabled build and a malicious SSH peer; the resulting memory pressure can interrupt the endpoint.

The record

CVE
CVE-2026-81535
Published
Oct 7, 2026
Updated
Oct 7, 2026
Vendor
wolfSSL
Product
wolfSSH
Classifications
T1499.004
Attack vector
network
Privileges
Unavailable

Timeline

How it unfolded

  1. Oct 7, 2026CVE publishedPublication date reported by the CVE source.
  2. Oct 7, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1.4.8 <=1.5.0 changes=[{"at":"1.6.0","status":"unaffected"}]

What conditions does exploitation require?

Attack vectornetwork
Required privilegesUnavailable in this record.

What is affected?

wolfSSL · wolfSSHversion=1.4.8 <=1.5.0 changes=[{"at":"1.6.0","status":"unaffected"}]

Published CVSS scores

No CVSS assessment is available in this record.

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Get started to see how Hinoki identifies affected software and validates exploitability in your environment.

Get started