How severe is CVE-2021-34558?

CVE-2021-34558 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-34558 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 7% (93rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-34558?

CVE-2021-34558 primarily affects Golang Go. In total, 7 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-34558?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-34558 published?

CVE-2021-34558 was published on 2021-07-15 and last updated on 2026-06-17.

CVE-2021-34558

CVE-2021-34558 is a medium-severity vulnerability in Golang Go with a CVSS 3.x base score of 6.5. 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-295.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v2: 2.6
EPSS exploit prediction: 7% (93rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-295
Affected product: Golang Go
Published: 2021-07-15
Last modified: 2026-06-17

Description

The crypto/tls package of Go through 1.16.5 does not properly assert that the type of public key in an X.509 certificate matches the expected type when doing a RSA based key exchange, allowing a malicious TLS server to cause a TLS client to panic.

Frequently asked questions

What is CVE-2021-34558?: The crypto/tls package of Go through 1.16.5 does not properly assert that the type of public key in an X.509 certificate matches the expected type when doing a RSA based key exchange, allowing a malicious TLS server to cause a TLS client to panic.
How severe is CVE-2021-34558?: CVE-2021-34558 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-34558 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 7% (93rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-34558?: CVE-2021-34558 primarily affects Golang Go. In total, 7 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-34558?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-34558 published?: CVE-2021-34558 was published on 2021-07-15 and last updated on 2026-06-17.

References

Affected products (7)

cpe:2.3:a:golang:go:*:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
cpe:2.3:a:netapp:cloud_insights_telegraf:-:*:*:*:*:*:*:*
cpe:2.3:a:netapp:storagegrid:-:*:*:*:*:*:*:*
cpe:2.3:a:netapp:trident:-:*:*:*:*:*:*:*
cpe:2.3:a:oracle:timesten_in-memory_database:*:*:*:*:*:*:*:*

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