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CVE-2021-28484

24
FAUCET Score

CVE-2021-28484 is a denial-of-service vulnerability affecting Yubico yubihsm-connector versions prior to 3.0.1, specifically within the /api/connector endpoint handler. An unauthenticated attacker can send a malformed, short request (0-2 bytes) to the connector, causing it to enter an infinite loop while awaiting data from the YubiHSM, thereby preventing further operations until a restart. Rated High (CVSS 7.5), this vulnerability has a network attack vector, low attack complexity, and high availability impact, with no confidentiality or integrity impact. There is currently no public exploit code, active exploitation, or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 3.0.1CPE matchmatch criteria
cpe:2.3:a:yubico:yubihsm_connector:*:*:*:*:*:*:*:*
34CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.5HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.52%
Probability of exploitation in next 30 days
EPSS Percentile
72.0%
Percentile rank of EPSS score among Peer Group
As of 2026-07-26
Model: v2026.06.15
This CVE's current EPSS score of 0.0152 is in the 54th percentile among its peer group of 51,485 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (1)

gopatch availablevia ghsa
Product: github.com/Yubico/yubihsm-connectorFixed in: 3.0.1

Vendor Advisories (1)

goGHSA-8m9g-647g-5pxwhigh

Infinite loop in Yubico yubihsm-connector

Feb 15, 2022

References

github.com / Yubico/yubihsm-connector/releases
Third Party Advisory
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/B7Q2KGXSPQEEONAWMFZRVH2TXWX3QPCQ
yubico.com / support/security-advisories/ysa-2021-02
Vendor Advisory