How severe is CVE-2020-24387?

CVE-2020-24387 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2020-24387 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (75th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-24387?

CVE-2020-24387 primarily affects Yubico Yubihsm-shell. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2020-24387?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2020-24387 published?

CVE-2020-24387 was published on 2020-10-19 and last updated on 2026-06-17.

CVE-2020-24387

CVE-2020-24387 is a high-severity vulnerability in Yubico Yubihsm-shell with a CVSS 3.x base score of 7.5. 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-125.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 2% (75th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-125
Affected product: Yubico Yubihsm-shell
Published: 2020-10-19
Last modified: 2026-06-17

Description

An issue was discovered in the yh_create_session() function of yubihsm-shell through 2.0.2. The function does not explicitly check the returned session id from the device. An invalid session id would lead to out-of-bounds read and write operations in the session array. This could be used by an attacker to cause a denial of service attack.

Frequently asked questions

What is CVE-2020-24387?: An issue was discovered in the yh_create_session() function of yubihsm-shell through 2.0.2. The function does not explicitly check the returned session id from the device. An invalid session id would lead to out-of-bounds read and write operations in the session array. This could be used by an attacker to cause a denial of service attack.
How severe is CVE-2020-24387?: CVE-2020-24387 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2020-24387 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (75th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-24387?: CVE-2020-24387 primarily affects Yubico Yubihsm-shell. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2020-24387?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2020-24387 published?: CVE-2020-24387 was published on 2020-10-19 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:a:yubico:yubihsm-shell:*:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*

More vulnerabilities in Yubico Yubihsm-shell

CVE-2020-24388 — High (CVSS 7.5): An issue was discovered in the _send_secure_msg() function of yubihsm-shell through 2.0.2. The function does not…
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