Out-of-bounds Read in Yubico Yubihsm-Shell

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.

Vulnerability class: Buffer Overflow

EPSS: 0.016 (73.2th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 4.4 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H.

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2021-27217?
CVE-2021-27217 is a medium-severity vulnerability in Yubico Yubihsm-Shell, classified under Out-of-bounds Read. CVSS score: 4.4/10. Published 2021-03-04.
How severe is CVE-2021-27217?
Medium severity. CVSS v3 base score is 4.4 out of 10.