How severe is CVE-2017-6542?

CVE-2017-6542 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2017-6542 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 22% (97th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2017-6542?

CVE-2017-6542 primarily affects Putty. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2017-6542?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2017-6542 published?

CVE-2017-6542 was published on 2017-03-27 and last updated on 2026-06-17.

CVE-2017-6542

CVE-2017-6542 is a critical-severity vulnerability in Putty with a CVSS 3.x base score of 9.8. Its EPSS exploit-prediction score of 22% places it in the 97th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-119.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 22% (97th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-119
Affected product: Putty
Published: 2017-03-27
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2017-6542?: 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.
How severe is CVE-2017-6542?: CVE-2017-6542 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2017-6542 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 22% (97th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2017-6542?: CVE-2017-6542 primarily affects Putty. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2017-6542?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2017-6542 published?: CVE-2017-6542 was published on 2017-03-27 and last updated on 2026-06-17.

References

Affected products (3)

cpe:2.3:a:putty:putty:*:*:*:*:*:*:*:*
cpe:2.3:o:opensuse:leap:42.2:*:*:*:*:*:*:*
cpe:2.3:o:opensuse_project:leap:42.1:*:*:*:*:*:*:*

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