Unsigned to Signed Conversion Error (CWE-196) vulnerability exists in TTSSH2 plugin of Tera Term provided by TeraTerm Project. When Tera Term attempts to establish an SSH connection to a server set up by an attacker, out-of-bounds read/write may occur. As a result, the contents of adjacent memory regions may be transmitted to the server, and Tera Term may behave unexpected or terminate abnormally.

Attack Vector Network

Attack Complexity Low

Privileges Required None

Attack Requirements None

User Interaction Active

Vulnerable System Confidentiality Impact Low

Vulnerable System Integrity Impact Low

Vulnerable System Availability Impact Low

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

No CVSS v3.1

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact Low

Integrity Impact Low

Availability Impact Low

User Interaction Required

No CVSS v2

This CVE is not in the KEV list.

The EPSS score is 0.0032.

Exploitation none

Automatable no

Technical Impact partial

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
TeraTerm Project TTSSH2 unaffected
Version Status Constraints
1.00 alpha1 affected ≤ 3.6.1

No data.

No data.

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Vendors Products
Teraterm Project Subscribe
Ttssh2 Subscribe

Project Subscriptions

Vendors Products
Teraterm Project Subscribe
Ttssh2 Subscribe
Advisories

No advisories yet.

Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://jvn.jp/en/jp/JVN65294474/ cve-icon
https://teratermproject.github.io/SA/JVN65294474-en.html cve-icon
https://teratermproject.github.io/SA/JVN65294474.html cve-icon
History

Thu, 23 Jul 2026 22:45:00 +0000

Type Values Removed Values Added
First Time appeared Teraterm Project
Teraterm Project ttssh2
Vendors & Products Teraterm Project
Teraterm Project ttssh2

Wed, 22 Jul 2026 03:30:00 +0000

Type Values Removed Values Added
Title Unsigned to Signed Conversion Error Leading to Out-of-Bounds Read/Write in TTSSH2

Fri, 17 Jul 2026 13:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Fri, 17 Jul 2026 05:00:00 +0000

Type Values Removed Values Added
Description Unsigned to Signed Conversion Error (CWE-196) vulnerability exists in TTSSH2 plugin of Tera Term provided by TeraTerm Project. When Tera Term attempts to establish an SSH connection to a server set up by an attacker, out-of-bounds read/write may occur. As a result, the contents of adjacent memory regions may be transmitted to the server, and Tera Term may behave unexpected or terminate abnormally.
Weaknesses CWE-196
References
Metrics cvssV3_0

{'score': 6.3, 'vector': 'CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L'}

cvssV4_0

{'score': 5.1, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: jpcert

Published:

Updated: 2026-07-17T13:06:39.880Z

Reserved: 2026-07-10T02:15:08.138Z

Link: CVE-2026-58317

cve-icon Vulnrichment

Updated: 2026-07-17T13:06:24.093Z

cve-icon NVD

No data.

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-07-23T22:09:24Z

Weaknesses