CVE-2026-35388

Unauthorized proxy sessions via skipped confirmation

Published Apr 2, 2026 · Updated Apr 2, 2026

Improper confirmation in OpenSSH before 10.3 allows local users to open proxy-mode multiplexing sessions without user approval. The ssh client fails to apply ControlMaster ask or autoask confirmation when its multiplex handler processes an ssh -O proxy request. Exploitation requires access to the master's local control socket and permits reuse of its established SSH connection as a proxy.

CVSS severity2.5
Low
EPSS probability0.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper confirmation in OpenSSH before 10.3 allows local users to open proxy-mode multiplexing sessions without user approval. The ssh client fails to apply ControlMaster ask or autoask confirmation when its multiplex handler processes an ssh -O proxy request. Exploitation requires access to the master's local control socket and permits reuse of its established SSH connection as a proxy.

The record

CVE
CVE-2026-35388
Published
Apr 2, 2026
Updated
Apr 2, 2026
Vendor
OpenBSD Project
Product
OpenSSH
Classifications
CWE-420, T1090
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

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

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=0 <10.3

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

OpenBSD Project · OpenSSHversion=0 <10.3

Published CVSS scores

2.5MITRE CorporationCVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:N

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.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-420Unprotected Alternate Channel
T1090Proxy

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

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Your stack

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