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CVE-2017-6542

The ssh_agent_channel_data function in PuTTY before 0.68 allows remote attackers to have...

9.8 CriticalPublic exploitFix available

The ssh_agent_channel_data function in PuTTY before 0.68 allows remote attackers to have unspecified impact via a large length value in an agent protocol message and leveraging the ability to connect to the Unix-domain socket representing the forwarded agent connection, which trigger a buffer overflow.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
High

Exploit likelihood

21.8%Up 12.1 points since Apr 14, 2021
90%50%10%1%

What each source reports

NVD Score used 9.8

The ssh_agent_channel_data function in PuTTY before 0.68 allows remote attackers to have unspecified impact via a large length value in an agent protocol message and leveraging the ability to connect to the Unix-domain socket representing the forwarded agent connection, which trigger a buffer overflow.

Record
CVE-2017-6542
CVSS 3.0
9.8 CriticalCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS 2.0
7.5 HighAV:N/AC:L/Au:N/C:P/I:P/A:P
Weakness
CWE-119
Updated
2026-11-02
CVE List No score

The ssh_agent_channel_data function in PuTTY before 0.68 allows remote attackers to have unspecified impact via a large length value in an agent protocol message and leveraging the ability to connect to the Unix-domain socket representing the forwarded agent connection, which trigger a buffer overflow.

Record
CVE-2017-6542
Updated
2026-11-02
EUVDEUVD-2017-15598 No score

The ssh_agent_channel_data function in PuTTY before 0.68 allows remote attackers to have unspecified impact via a large length value in an agent protocol message and leveraging the ability to connect to the Unix-domain socket representing the forwarded agent connection, which trigger a buffer overflow.

Record
EUVD-2017-15598
Updated
2026-11-03
GitHub AdvisoriesGHSA-6q3h-v425-7xx2 9.8

The ssh_agent_channel_data function in PuTTY before 0.68 allows remote attackers to have...

The ssh_agent_channel_data function in PuTTY before 0.68 allows remote attackers to have unspecified impact via a large length value in an agent protocol message and leveraging the ability to connect to the Unix-domain socket representing the forwarded agent connection, which trigger a buffer overflow.

Record
GHSA-6q3h-v425-7xx2
CVSS 3.0
9.8 CriticalCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-119
Updated
2026-11-02
OSVALPINE-CVE-2017-6542 9.8

The ssh_agent_channel_data function in PuTTY before 0.68 allows remote attackers to have unspecified impact via a large length value in an agent protocol message and leveraging the ability to connect to the Unix-domain socket representing the forwarded agent connection, which trigger a buffer overflow.

Record
ALPINE-CVE-2017-6542
CVSS 3.0
9.8 CriticalCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSV 9.8

The ssh_agent_channel_data function in PuTTY before 0.68 allows remote attackers to have unspecified impact via a large length value in an agent protocol message and leveraging the ability to connect to the Unix-domain socket representing the forwarded agent connection, which trigger a buffer overflow.

Record
CVE-2017-6542
CVSS 3.0
9.8 CriticalCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
Show 4 moreShow less
OSVDEBIAN-CVE-2017-6542 9.8

The ssh_agent_channel_data function in PuTTY before 0.68 allows remote attackers to have unspecified impact via a large length value in an agent protocol message and leveraging the ability to connect to the Unix-domain socket representing the forwarded agent connection, which trigger a buffer overflow.

Record
DEBIAN-CVE-2017-6542
CVSS 3.0
9.8 CriticalCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2017-6542 9.8

The ssh_agent_channel_data function in PuTTY before 0.68 allows remote attackers to have unspecified impact via a large length value in an agent protocol message and leveraging the ability to connect to the Unix-domain socket representing the forwarded agent connection, which trigger a buffer overflow.

Record
UBUNTU-CVE-2017-6542
CVSS 3.0
9.8 CriticalCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVMGASA-2017-0093 No score

Updated putty packages fix security vulnerability

In PuTTY before 0.68, if SSH agent forwarding is enabled, local attackers that are also able to connect to the UNIX domain socket could have overwritten heap data (CVE-2017-6542).

Record
MGASA-2017-0093
Updated
2026-11-02
OSVopenSUSE-SU-2024:11201-1 No score

putty-0.76-1.2 on GA media

These are all security issues fixed in the putty-0.76-1.2 package on the GA media of openSUSE Tumbleweed.

Record
openSUSE-SU-2024:11201-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
putty
Alpine:v3.2
 before 0.68-r0
0.68-r0
putty
Alpine:v3.3
 before 0.68-r0
0.68-r0
putty
Alpine:v3.4
 before 0.68-r0
0.68-r0
putty
Alpine:v3.5
 before 0.68-r0
0.68-r0
putty
Debian:12
 before 0.67-3
0.67-3
putty
Debian:13
 before 0.67-3
0.67-3
putty
Debian:14
 before 0.67-3
0.67-3
putty
Mageia:5
 before 0.68-1.mga5
0.68-1.mga5
putty
Ubuntu:16.04:LTS
 before 0.67-3build0.16.04.1, plus listed versions
0.65-20.66-10.66-20.66-30.66-40.67-10.67-2
0.67-3build0.16.04.1
putty
openSUSE:Tumbleweed
 before 0.76-1.2
0.76-1.2

Public exploits

Links only. Every CVE stores no exploit code.

Public exploits
SourceLinkDate
Exploit-DBPuTTY < 0.68 - 'ssh_agent_channel_data' Integer Overflow Heap Corruption2017-06-07

History

History
RecordedChangedSources
aliasesEUVD
first indexedCVE List, Exploit-DB, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2017-6542 is a critical vulnerability (CVSS 9.8) in Putty, published March 27, 2017. Public exploit code exists. EPSS puts the chance of exploitation in the next 30 days at 21.8%, the 97th percentile. Fixed in putty 0.68-r0.

References

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