How severe is CVE-2021-27217?

CVE-2021-27217 has a CVSS 3.x base score of 4.4, rated medium severity. It is exploitable over network with high attack complexity, requires high privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-27217 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-2021-27217?

CVE-2021-27217 affects Yubico Yubihsm-shell. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-27217?

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

When was CVE-2021-27217 published?

CVE-2021-27217 was published on 2021-03-04 and last updated on 2026-06-17.

CVE-2021-27217

CVE-2021-27217 is a medium-severity vulnerability in Yubico Yubihsm-shell with a CVSS 3.x base score of 4.4. 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-125.

Key facts

Severity: Medium (CVSS 3.x base score 4.4)
CVSS v2: 3.5
EPSS exploit prediction: 2% (73rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-125
Affected product: Yubico Yubihsm-shell
Published: 2021-03-04
Last modified: 2026-06-17

Description

An issue was discovered in the _send_secure_msg() function of Yubico yubihsm-shell through 2.0.3. The function does not correctly validate the embedded length field of an authenticated message received from the device. Out-of-bounds reads performed by aes_remove_padding() can crash the running process, depending on the memory layout. This could be used by an attacker to cause a client-side denial of service. The yubihsm-shell project is included in the YubiHSM 2 SDK product.

Frequently asked questions

What is CVE-2021-27217?: An issue was discovered in the _send_secure_msg() function of Yubico yubihsm-shell through 2.0.3. The function does not correctly validate the embedded length field of an authenticated message received from the device. Out-of-bounds reads performed by aes_remove_padding() can crash the running process, depending on the memory layout. This could be used by an attacker to cause a client-side denial of service. The yubihsm-shell project is included in the YubiHSM 2 SDK product.
How severe is CVE-2021-27217?: CVE-2021-27217 has a CVSS 3.x base score of 4.4, rated medium severity. It is exploitable over network with high attack complexity, requires high privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-27217 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-2021-27217?: CVE-2021-27217 affects Yubico Yubihsm-shell. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-27217?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-27217 published?: CVE-2021-27217 was published on 2021-03-04 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:yubico:yubihsm-shell:*:*:*:*:*:*:*:*

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