How severe is CVE-2021-27891?

CVE-2021-27891 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-27891 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (60th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-27891?

CVE-2021-27891 primarily affects Ssh Tectia Client. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-27891?

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

When was CVE-2021-27891 published?

CVE-2021-27891 was published on 2021-03-15 and last updated on 2026-06-17.

CVE-2021-27891

CVE-2021-27891 is a high-severity vulnerability in Ssh Tectia Client with a CVSS 3.x base score of 8.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Severity: High (CVSS 3.x base score 8.8)
CVSS v2: 6.5
EPSS exploit prediction: 1% (60th percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Ssh Tectia Client
Published: 2021-03-15
Last modified: 2026-06-17

Description

SSH Tectia Client and Server before 6.4.19 on Windows have weak key generation. ConnectSecure on Windows is affected.

Frequently asked questions

What is CVE-2021-27891?: SSH Tectia Client and Server before 6.4.19 on Windows have weak key generation. ConnectSecure on Windows is affected.
How severe is CVE-2021-27891?: CVE-2021-27891 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-27891 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (60th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-27891?: CVE-2021-27891 primarily affects Ssh Tectia Client. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-27891?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-27891 published?: CVE-2021-27891 was published on 2021-03-15 and last updated on 2026-06-17.

References

https://info.ssh.com/tectia-vulnerability-cve-2021-27891

Affected products (3)

cpe:2.3:a:ssh:tectia_client:*:*:*:*:*:*:*:*
cpe:2.3:a:ssh:tectia_connectsecure:-:*:*:*:*:*:*:*
cpe:2.3:a:ssh:tectia_server:*:*:*:*:*:*:*:*

More vulnerabilities in Ssh Tectia Client

CVE-2021-27892 — High (CVSS 7.8): SSH Tectia Client and Server before 6.4.19 on Windows allow local privilege escalation. ConnectSecure on Windows is…
CVE-2007-5616 — High (CVSS 7.2): ssh-signer in SSH Tectia Client and Server 5.x before 5.2.4, and 5.3.x before 5.3.6, on Unix and Linux allows local…
CVE-2006-4315 — High (CVSS 7.2): Unquoted Windows search path vulnerability in multiple SSH Tectia products, including Client/Server/Connector 5.0.0 and…
CVE-2021-27893 — High (CVSS 7.0): SSH Tectia Client and Server before 6.4.19 on Windows allow local privilege escalation in nonstandard conditions.…
CVE-2006-5484 — Medium (CVSS 5.0): SSH Tectia Client/Server/Connector 5.1.0 and earlier, Manager 2.2.0 and earlier, and other products, when using an RSA…
CVE-2008-5161 — Low (CVSS 3.7): Error handling in the SSH protocol in (1) SSH Tectia Client and Server and Connector 4.0 through 4.4.11, 5.0 through…

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