CVE-2021-28484 Infinite loop in Yubico yubihsm-connector

What is CVE-2021-28484?

CVE-2021-28484 is a high-severity denial of service vulnerability in Fedoraproject Fedora, published on 14 Apr 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

An issue was discovered in the /api/connector endpoint handler in Yubico yubihsm-connector before 3.0.1 (in YubiHSM SDK before 2021.04). The handler did not validate the length of the request, which can lead to a state where yubihsm-connector becomes stuck in a loop waiting for the YubiHSM to send it data, preventing any further operations until the yubihsm-connector is restarted. An attacker can send 0, 1, or 2 bytes to trigger this.

Weakness: CWE-835

Which versions are affected by CVE-2021-28484?

2 open source packages ship an affected version, including github.com/Yubico/yubihsm-connector. It affects 2 products.

Products include Fedoraproject Fedora, Yubico Yubihsm Connector.

How do I fix CVE-2021-28484?

Upgrade github.com/Yubico/yubihsm-connector to 3.0.1 or later.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2021-28484 being exploited?

There is no known exploitation of CVE-2021-28484 in the wild and no public exploit code.

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All Fedoraproject Fedora vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-8m9g-647g-5pxw.