HOMEVULNERABILITIESCVE-2021-27217
MEDIUM

CVE-2021-27217

CWE-125Published: March 4, 2021· Updated: Jun 17, 2026

4.4
CVSS v3.1

Official 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.

NVD Source

Technical Analysis

CVE-2021-27217 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

Exploitation requires high privileges, which limits the exposure to scenarios where an attacker has already gained initial access.

A successful exploit results in availability disruption (denial of service), with a CVSS base score of 4.4.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityHigh
Privileges Req.High
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityNone
IntegrityNone
AvailabilityHigh
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H

Affected Vendors & Products

yubico1 product(s)
yubihsm-shell
Source: NVD CPE · 1 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

ADVISORYhttps://blog.inhq.net/posts/yubico-libyubihsm-vuln2
ADVISORYhttps://github.com/Yubico/yubihsm-shell/releases
ADVISORYhttps://www.yubico.com/support/security-advisories/ysa-2021-01/
ADVISORYhttps://blog.inhq.net/posts/yubico-libyubihsm-vuln2
ADVISORYhttps://github.com/Yubico/yubihsm-shell/releases
ADVISORYhttps://www.yubico.com/support/security-advisories/ysa-2021-01/

All References (6)

→
https://blog.inhq.net/posts/yubico-libyubihsm-vuln2Exploit · Third Party Advisory
→
https://github.com/Yubico/yubihsm-shell/releasesRelease Notes · Third Party Advisory
→
https://www.yubico.com/support/security-advisories/ysa-2021-01/Vendor Advisory
→
https://blog.inhq.net/posts/yubico-libyubihsm-vuln2Exploit · Third Party Advisory
→
https://github.com/Yubico/yubihsm-shell/releasesRelease Notes · Third Party Advisory
→
https://www.yubico.com/support/security-advisories/ysa-2021-01/Vendor Advisory

Quick Facts

CVE IDCVE-2021-27217
CVSS Score4.4 / 10
SeverityMEDIUM
WeaknessCWE-125
CISA KEVNo
Affected1 vendor(s)
PublishedMar 4, 2021

Related CVEs (CWE-125)

CVE-2009-2523
10.0
CVE-2026-24826
10.0
CVE-2013-0767
10.0
CVE-2021-41556
10.0
CVE-2021-21777
10.0
CVE-2017-14451
10.0

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2021-27217 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWatch. CVE data is provided under the NVD usage policy.
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