How severe is CVE-2021-26307?

CVE-2021-26307 has a CVSS score of 5.5/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which products are affected by CVE-2021-26307?

CVE-2021-26307 affects the following products: raw-cpuid_project raw-cpuid.

How do I patch CVE-2021-26307?

Apply the raw-cpuid_project raw-cpuid security patch or hotfix for CVE-2021-26307 on the affected version, following the vendor advisory for your exact build.

How do I detect CVE-2021-26307 across my infrastructure?

Inventory every raw-cpuid_project raw-cpuid deployment and check each version against the affected-products list above.

How do I mitigate CVE-2021-26307 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands. Alongside that, restrict the management interface to trusted networks and apply the vendor's recommended configuration mitigations.

Is CVE-2021-26307 actively exploited in the wild?

Yes. There are 1 known exploit references for CVE-2021-26307, including 1 in-the-wild exploitation observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2021-26307?

CVE-2021-26307 has an EPSS (Exploit Prediction Scoring System) score of 0.3%, placing it in the 28th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

Which products and versions are affected by CVE-2021-26307?

CVE-2021-26307 affects raw-cpuid_project raw-cpuid. Check the affected-products list on this page against your deployed version to confirm exposure.

When was CVE-2021-26307 published, and has it been updated?

CVE-2021-26307 was published on January 29, 2021 and was last updated on June 17, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🛡️

Not in CISA KEV

MEDIUM severity

CVE-2021-26307 — Raw-Cpuid

MEDIUM

CVE-2021-26307 is a medium-severity (CVSS 5.5) vulnerability in raw-cpuid_project raw-cpuid. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available — see the affected versions and patch details below.

An issue was discovered in the raw-cpuid crate before 9.0.0 for Rust. It allows __cpuid_count() calls even if the processor does not support the CPUID instruction, which is unsound…

Published

Jan 29, 2021

Updated

Jun 17, 2026

Affected

1 product

Patched

See advisory

Exploits

1 known

Exploitation data as of Oct 31, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

0.3%probability of exploitation in next 30 days

Lower Risk+0.01%

Lower risk than most CVEs28th percentile — riskier than 28% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Description

An issue was discovered in the raw-cpuid crate before 9.0.0 for Rust. It allows __cpuid_count() calls even if the processor does not support the CPUID instruction, which is unsound and causes a deterministic crash.

Affected Products

1 product · 1 configurations

Application

raw-cpuidraw-cpuid_project

< 9.0.0

range

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

An issue was discovered in the raw-cpuid crate before 9.0.0 for Rust. It…

rustsec.orgNVDFeb 2021

Detection & mitigation playbook

Vendor / appliance

Detect
Inventory every raw-cpuid_project raw-cpuid deployment and check each version against the affected-products list above.
Fix
Apply the raw-cpuid_project raw-cpuid security patch or hotfix for CVE-2021-26307 on the affected version, following the vendor advisory for your exact build.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands. Alongside that, restrict the management interface to trusted networks and apply the vendor's recommended configuration mitigations.

Frequently Asked Questions

O3 Security · Runtime Protection

Is CVE-2021-26307 being exploited in your environment?

Detect and block the exploit chain at execution, on systems you cannot patch yet.

Protect my workloads How runtime protection works