Integer overflow in Yubico Yubihsm-Shell

CVE-2021-32489

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 because response_msg.st.len=8 can be accepted but triggers an integer overflow, which causes CRYPTO_cbc128_decrypt (in OpenSSL) to encounter an undersized buffer and experience a segmentation fault. The yubihsm-shell project is included in the YubiHSM 2 SDK product.

Vulnerability class: Integer Overflow

Published · last modified .

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.

EPSS exploit prediction

EPSS: 0.009 (58.8th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 59th percentile — 58.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2021-32489: held from 0.009 to 0.009.

EPSS over last 30 days · oldest: 0.009 · newest: 0.009 · change: 0.000

Affected products

Weakness classification (CWE)

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2021-32489?
CVE-2021-32489 is a medium-severity vulnerability in Yubico Yubihsm-Shell, classified under Integer Overflow or Wraparound. CVSS score: 4.4/10. Published 2021-05-10.
How severe is CVE-2021-32489?
Medium severity. CVSS v3 base score is 4.4 out of 10.
Is CVE-2021-32489 known to be exploited?
2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.