Putty
CVE-2019-9895
CRITICAL
Vulnerability Assessment
| Weakness |
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Bounds checking, buffer size validation
MITRE ATT&CK
2 techniques across 2 tactics: Execution, Privilege Escalation The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Impact | CVSS score of 9.8 (CRITICAL). Attack characteristics: network attack vector, low complexity, no privileges required, no user interaction not required. |
| Exploit ScenarioDerived | A remote attacker could corrupt memory to execute arbitrary code or crash the application by sending crafted requests to the affected application. No authentication is required to exploit this vulnerability. |
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Alert meAnalysisAI
In PuTTY versions before 0.71 on Unix, a remotely triggerable buffer overflow exists in any kind of server-to-client forwarding. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
RemediationAI
No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Use memory-safe languages or bounds-checking. Enable ASLR, DEP/NX, stack canaries. Use safe string functions.
Affects your stack
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Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
This vulnerability is classified as Buffer Overflow (CWE-119), which allows attackers to corrupt memory to execute arbitrary code or crash the application. In PuTTY versions before 0.71 on Unix, a remotely triggerable buffer overflow exists in any kind of server-to-client forwarding. Affected products include: Putty, Fedoraproject Fedora. Version information: before 0.71.
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- Exploit and PoC references, threat intelligence from 22 sources
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Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
DescriptionNVD
In PuTTY versions before 0.71 on Unix, a remotely triggerable buffer overflow exists in any kind of server-to-client forwarding.
Threat Intelligence Overview
NVD
CVE.org
EPSS
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.
Affected Products (CPE)NVD
The SSH transport protocol with certain OpenSSH extensions, found in OpenSSH before 9.6 and other products, allows remot
Stack-based buffer overflow in the SCP command-line utility in PuTTY before 0.67 and KiTTY 0.66.6.3 and earlier allows r
The ssh_agent_channel_data function in PuTTY before 0.68 allows remote attackers to have unspecified impact via a large
Multiple untrusted search path vulnerabilities in Putty beta 0.67 allow local users to execute arbitrary code and conduc
PuTTY before 0.75 on Windows allows remote servers to cause a denial of service (Windows GUI hang) by telling the PuTTY
PuTTY before 0.73 on Windows improperly opens port-forwarding listening sockets, which allows attackers to listen on the
Potential recycling of random numbers used in cryptography exists within PuTTY before 0.71. Rated critical severity (CVS
PuTTY through 0.75 proceeds with establishing an SSH session even if it has never sent a substantive authentication resp
In PuTTY versions before 0.71 on Windows, local attackers could hijack the application by putting a malicious help file
PuTTY before 0.73 might allow remote SSH-1 servers to cause a denial of service by accessing freed memory locations via
PuTTY before 0.73 mishandles the "bracketed paste mode" protection mechanism, which may allow a session to be affected b
Multiple denial-of-service attacks that can be triggered by writing to the terminal exist in PuTTY versions before 0.71.
GitHub PoC
Exploit-DB