CVE-2021-27217

low-risk
Published 2021-03-04

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.

Do I need to act?

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0.61% chance of exploitation
EPSS score — low exploit probability
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Not on CISA KEV list
No confirmed active exploitation reported to CISA
?
Patch status unknown
Check vendor advisories for fix availability and mitigation guidance
4
CVSS 4.4/10 Medium
NETWORK / HIGH complexity

Affected Products (1)

Yubihsm-Shell

Affected Vendors

Yubico

References (6)

Exploit https://blog.inhq.net/posts/yubico-libyubihsm-vuln2
Release Notes https://github.com/Yubico/yubihsm-shell/releases
Vendor Advisory https://www.yubico.com/support/security-advisories/ysa-2021-01/
Exploit https://blog.inhq.net/posts/yubico-libyubihsm-vuln2
Release Notes https://github.com/Yubico/yubihsm-shell/releases
Vendor Advisory https://www.yubico.com/support/security-advisories/ysa-2021-01/
21
/ 100
low-risk
Severity 14/34 · Moderate
Exploitability 2/34 · Minimal
Exposure 5/34 · Minimal