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VulnerabilityPublished

CVE-2026-35388: OpenBSD OpenSSH · Unprotected Alternate Channel

Affects OpenBSD OpenSSHSource CVE Database V5

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Not known to be exploited · CVSS 2.5 Low : upgrade to 10.3 when convenient.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score
2.5Low
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 2% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 10.3
CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 2 Apr 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

What to do

Upgrade OpenBSD OpenSSH to 10.3.

Affected software

ProductAffectedFixed in
OpenBSDOpenSSHAffected
  • <10.3
Fixed in
  • 10.3

AI-suggested

If you cannot patch yet, users should consider avoiding proxy-mode multiplexing sessions or restrict local access to trusted users to reduce risk.

Description

CVE-2026-35388 is a low-severity vulnerability in OpenSSH versions before 10.3 where connection multiplexing confirmation is omitted for proxy-mode multiplexing sessions. This issue relates to CWE-420, an unprotected alternate channel, potentially allowing limited unauthorized interaction. The vulnerability does not impact confidentiality or availability but may cause limited integrity issues.

References

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