OpenSSH up to 10.2 Proxy-mode Multiplexing Session unprotected alternate channel

CVSS Meta Temp Score
CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.
Current Exploit Price (≈)
Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.
CTI Interest Score
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
2.5$0-$5k0.00

Summaryinfo

A vulnerability was found in OpenSSH up to 10.2. It has been classified as problematic. This affects an unknown part of the component Proxy-mode Multiplexing Session Handler. This manipulation causes unprotected alternate channel. This vulnerability is handled as CVE-2026-35388. It is possible to launch the attack on the local host. There is not any exploit available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability classified as problematic was found in OpenSSH up to 10.2. Affected by this vulnerability is an unknown code block of the component Proxy-mode Multiplexing Session Handler. The manipulation with an unknown input leads to a unprotected alternate channel vulnerability. The CWE definition for the vulnerability is CWE-420. The product protects a primary channel, but it does not use the same level of protection for an alternate channel. As an impact it is known to affect integrity. The summary by CVE is:

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

The advisory is shared at openssh.org. This vulnerability is known as CVE-2026-35388 since 04/02/2026. The exploitation appears to be difficult. An attack has to be approached locally. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 07/26/2026).

The vulnerability scanner Nessus provides a plugin with the ID 306743 (OpenSSH < 10.3 Multiple Vulnerabilities), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 10.3 eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (306743) and CERT Bund (WID-SEC-2026-0979). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Affected

  • IBM AIX
  • IBM VIOS
  • Google Container-Optimized OS
  • Debian Linux
  • Amazon Linux 2
  • Red Hat Enterprise Linux
  • Fedora Linux
  • Ubuntu Linux
  • SUSE Linux
  • Oracle Linux
  • SUSE openSUSE
  • RESF Rocky Linux
  • NetApp ActiveIQ Unified Manager
  • Microsoft Azure Linux
  • Open Source OpenSSH
  • Red Hat OpenShift

Productinfo

Type

Name

Version

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 2.5
VulDB Meta Temp Score: 2.5

VulDB Base Score: 2.5
VulDB Temp Score: 2.4
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 2.5
NVD Vector: 🔒

CNA Base Score: 2.5
CNA Vector (MITRE): 🔒

CVSSv2info

AVACAuCIA
💳💳💳💳💳💳
💳💳💳💳💳💳
💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
UnlockUnlockUnlockUnlockUnlockUnlock
UnlockUnlockUnlockUnlockUnlockUnlock
UnlockUnlockUnlockUnlockUnlockUnlock

VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Unprotected alternate channel
CWE: CWE-420 / CWE-419
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

0-DayUnlockUnlockUnlockUnlock
TodayUnlockUnlockUnlockUnlock

Nessus ID: 306743
Nessus Name: OpenSSH < 10.3 Multiple Vulnerabilities

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: OpenSSH 10.3

Timelineinfo

04/02/2026 Advisory disclosed
04/02/2026 +0 days CVE reserved
04/02/2026 +0 days VulDB entry created
07/26/2026 +115 days VulDB entry last update

Sourcesinfo

Advisory: openssh.org
Status: Confirmed

CVE: CVE-2026-35388 (🔒)
GCVE (CVE): GCVE-0-2026-35388
GCVE (VulDB): GCVE-100-354961
CERT Bund: WID-SEC-2026-0979 - OpenSSH: Mehrere Schwachstellen

Entryinfo

Created: 04/02/2026 19:38
Updated: 07/26/2026 21:06
Changes: 04/02/2026 19:38 (63), 04/16/2026 23:06 (2), 05/04/2026 01:49 (7), 06/04/2026 04:47 (1), 07/26/2026 21:06 (11)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Discussion

No comments yet. Languages: en.

Please log in to comment.

◂ PreviousOverviewNext ▸

Want to know what is going to be exploited?

We predict KEV entries!