Putty
CVE-2019-9894
HIGH
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A04:2025 - Cryptographic Failures
ASVS 5.0
V11 - Cryptography Key management controls
|
| Impact | CVSS score of 7.5 (HIGH). Attack characteristics: network attack vector, low complexity, no privileges required, no user interaction not required. |
| Exploit ScenarioDerived | This vulnerability can be exploited remotely over the network. Successful exploitation could compromise the high-severity affected system. |
Get an e-mail when this CVE is exploited, patched or re-scored. Free account.
Alert meAnalysisAI
A remotely triggerable memory overwrite in RSA key exchange in PuTTY before 0.71 can occur before host key verification. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
RemediationAI
A vendor patch is available. Apply the latest security update as soon as possible. Apply vendor patches when available. Implement network segmentation and monitoring as interim mitigations.
Affects your stack
Find out whether the stacks and servers you run are on an affected version.
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 under CWE-320. A remotely triggerable memory overwrite in RSA key exchange in PuTTY before 0.71 can occur before host key verification. Affected products include: Putty, Fedoraproject Fedora, Debian Debian Linux, Netapp Oncommand Unified Manager, Opensuse Leap. Version information: before 0.71.
Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
DescriptionNVD
A remotely triggerable memory overwrite in RSA key exchange in PuTTY before 0.71 can occur before host key verification.
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
Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.
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
In PuTTY versions before 0.71 on Unix, a remotely triggerable buffer overflow exists in any kind of server-to-client for
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
GitHub PoC
Exploit-DB