# CVE-2026-83540: wolfSSL wolfSSHd Windows logon token release-of-resource vulnerability

Source: https://junglewise.ai/threats/cve-2026-83540-when-password-or-public-key-authentication-is-used-with-the  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-07. Updated: 2026-10-07  
License: CC BY 4.0 with a link back

CVE-2026-83540 · Severity: info · Published 2026-10-07

wolfSSHd is an embeddable SSH server that allows secure remote access to systems. On Windows, the server fails to release user authentication tokens from completed connections, allowing a low-privileged user to force the server to adopt the identity of a higher-privileged user for their own connections, potentially granting unauthorized access to sensitive data or functionality.

Technologies: [Wolfssl wolfSSH](https://junglewise.ai/threats/technologies/wolfssl-wolfssh). Vendors: [Wolfssl](https://junglewise.ai/threats/vendors/wolfssl).

## Quick answers

**Is CVE-2026-83540 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-83540 being exploited in the wild.

**How severe is CVE-2026-83540?** Informational severity, published 7 October 2026.

**Which products and versions are affected?** Wolfssl wolfSSH 1.4.15 through 1.5.0 (Windows port only).

**Is there a fix for CVE-2026-83540?** Yes: fixed in wolfSSH 1.5.1 or later. Until then: Disable password and public key authentication on Windows port of wolfSSHd, or restrict SSH access to trusted users only via firewall rules or authentication controls until patched. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-83540 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-83540?** Check whether you run Wolfssl wolfSSH at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in wolfSSH 1.5.1 or later

Disable password and public key authentication on Windows port of wolfSSHd, or restrict SSH access to trusted users only via firewall rules or authentication controls until patched.

## Technical details

When password or public key authentication is used on Windows, the wolfSSHd server does not release the Windows logon token acquired during one authenticated connection before acquiring a new token for a subsequent connection. This results in user login poisoning between connections. An attacker with valid credentials for a less-privileged account can trigger the server to adopt the identity of a more-privileged user, gaining unauthorized access to resources under that user's privileges.

## Affected products

- wolfSSL wolfSSH 1.4.15 through 1.5.0 (Windows port only)

## Timeline

- 2026-10-07: disclosed

## References

- [https://github.com/wolfSSL/wolfssh](https://github.com/wolfSSL/wolfssh)
- [https://github.com/wolfSSL/wolfssh/commit/9777bc5ce810d6c418a1473e9e8c40cdb0026e5a](https://github.com/wolfSSL/wolfssh/commit/9777bc5ce810d6c418a1473e9e8c40cdb0026e5a)

## Related threats

- [wolfSSL wolfSSH Diffie-Hellman group exchange message handling bypass](https://junglewise.ai/threats/cve-2026-84897-src-internal-c-in-wolfssl-wolfssh-through-1-5-0-admits-the-server)
- [wolfSSL wolfSSH unsigned integer underflow in wstrncat()](https://junglewise.ai/threats/cve-2026-83742-unsigned-integer-underflow-in-wstrncat-in-src-port-c-in-wolfssl)
- [wolfSSH forwarded-tcpip channel authorization bypass](https://junglewise.ai/threats/cve-2026-81535-in-wolfssh-through-1-5-0-built-with-enable-fwd-dochannelopen-in)
- [wolfSSH ECDSA curve substitution in host key parsing](https://junglewise.ai/threats/cve-2026-16516-wolfssh-does-not-validate-that-the-ecdsa-curve-identifier-in-a)