Memory disclosure and crash via unchecked packet lengths
Published Jul 17, 2026 · Updated Jul 17, 2026
Out-of-bounds access in TeraTerm Project TTSSH2 1.00 alpha1 through 3.6.1 allows remote attackers to read memory or crash Tera Term. TTSSH2 processes received SSH2 packet lengths without adequate validation, permitting out-of-bounds reads and limited null-byte writes. A user must connect to a malicious SSH server or through a man-in-the-middle attacker; adjacent memory can be returned to the server, while writes can disrupt or terminate the client.
Summary
What happened
Out-of-bounds access in TeraTerm Project TTSSH2 1.00 alpha1 through 3.6.1 allows remote attackers to read memory or crash Tera Term. TTSSH2 processes received SSH2 packet lengths without adequate validation, permitting out-of-bounds reads and limited null-byte writes. A user must connect to a malicious SSH server or through a man-in-the-middle attacker; adjacent memory can be returned to the server, while writes can disrupt or terminate the client.
The record
- CVE
- CVE-2026-58317
- Published
- Jul 17, 2026
- Updated
- Jul 17, 2026
- Vendor
- TeraTerm Project
- Product
- TTSSH2
- Classifications
- CWE-196, T1557
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 17, 2026CVE publishedPublication date reported by the CVE source.
- Jul 17, 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.
- Affected versionversion=1.00 alpha1 <=3.6.1
What conditions does exploitation require?
What is affected?
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.
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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