How severe is CVE-2019-17067?

CVE-2019-17067 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-2019-17067 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (73rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2019-17067?

CVE-2019-17067 affects Putty. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2019-17067?

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-2019-17067 published?

CVE-2019-17067 was published on 2019-10-01 and last updated on 2026-06-17.

CVE-2019-17067

CVE-2019-17067 is a critical-severity vulnerability in Putty with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-770.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 2% (73rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-770
Affected product: Putty
Published: 2019-10-01
Last modified: 2026-06-17

Description

PuTTY before 0.73 on Windows improperly opens port-forwarding listening sockets, which allows attackers to listen on the same port to steal an incoming connection.

Frequently asked questions

What is CVE-2019-17067?: PuTTY before 0.73 on Windows improperly opens port-forwarding listening sockets, which allows attackers to listen on the same port to steal an incoming connection.
How severe is CVE-2019-17067?: CVE-2019-17067 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-2019-17067 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (73rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2019-17067?: CVE-2019-17067 affects Putty. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2019-17067?: 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-2019-17067 published?: CVE-2019-17067 was published on 2019-10-01 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:putty:putty:*:*:*:*:*:*:*:*

More vulnerabilities in Putty

CVE-2004-1008 — Critical (CVSS 10.0): Integer signedness error in the ssh2_rdpkt function in PuTTY before 0.56 allows remote attackers to execute arbitrary…
CVE-2002-1359 — Critical (CVSS 10.0): Multiple SSH2 servers and clients do not properly handle large packets or large fields, which may allow remote…
CVE-2002-1358 — Critical (CVSS 10.0): Multiple SSH2 servers and clients do not properly handle lists with empty elements or strings, which may allow remote…
CVE-2002-1360 — Critical (CVSS 10.0): Multiple SSH2 servers and clients do not properly handle strings with null characters in them when the string length is…
CVE-2002-1357 — Critical (CVSS 10.0): Multiple SSH2 servers and clients do not properly handle packets or data elements with incorrect length specifiers,…
CVE-2019-9898 — Critical (CVSS 9.8): Potential recycling of random numbers used in cryptography exists within PuTTY before 0.71.

All CVEs affecting Putty →

Other CWE-770 (Allocation of Resources Without Limits or Throttling) vulnerabilities

CVE-2026-31283 — Critical (CVSS 9.8): In Totara LMS v19.1.5 and before, the forgot password API does not implement rate limiting for the target email…
CVE-2020-37067 — Critical (CVSS 9.8): Filetto 1.0 FTP server contains a denial of service vulnerability in the FEAT command processing that allows attackers…
CVE-2021-47875 — Critical (CVSS 9.8): GeoGebra CAS Calculator 6.0.631.0 contains a denial of service vulnerability that allows attackers to crash the…
CVE-2025-11832 — Critical (CVSS 9.8): Allocation of Resources Without Limits or Throttling vulnerability in Azure Access Technology BLU-IC2, Azure Access…
CVE-2024-44241 — Critical (CVSS 9.8): The issue was addressed with improved bounds checks. This issue is fixed in iOS 18.1 and iPadOS 18.1, macOS Sequoia…
CVE-2022-3439 — Critical (CVSS 9.8): Allocation of Resources Without Limits or Throttling in GitHub repository ikus060/rdiffweb prior to 2.5.0.

Browse all CWE-770 (Allocation of Resources Without Limits or Throttling) vulnerabilities →