What is GHSA-X5J2-G63M-F8G4?

GHSA-X5J2-G63M-F8G4 is a high-severity security vulnerability in pqc_kyber (rust), affecting versions <= 0.7.1. No fixed version is listed yet.

How severe is GHSA-X5J2-G63M-F8G4?

GHSA-X5J2-G63M-F8G4 has a CVSS score of 7.4 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.

Which versions of pqc_kyber are affected by GHSA-X5J2-G63M-F8G4?

pqc_kyber (rust) versions <= 0.7.1 is affected.

Is there a fix for GHSA-X5J2-G63M-F8G4?

No fixed version is listed for GHSA-X5J2-G63M-F8G4 yet. Monitor the advisory for updates and apply mitigations in the interim.

Is GHSA-X5J2-G63M-F8G4 exploitable, and should I be worried?

Whether GHSA-X5J2-G63M-F8G4 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk.

What actually determines whether GHSA-X5J2-G63M-F8G4 is exploitable, and how bad it is?

Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.

GHSA-X5J2-G63M-F8G4 in pqc_kyber

Q: How severe is GHSA-X5J2-G63M-F8G4?

GHSA-X5J2-G63M-F8G4 has a CVSS score of 7.4 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.

Q: Which versions of pqc_kyber are affected by GHSA-X5J2-G63M-F8G4?

pqc_kyber (rust) versions <= 0.7.1 is affected.

Q: Is there a fix for GHSA-X5J2-G63M-F8G4?

No fixed version is listed for GHSA-X5J2-G63M-F8G4 yet. Monitor the advisory for updates and apply mitigations in the interim.

Q: Is GHSA-X5J2-G63M-F8G4 exploitable, and should I be worried?

Whether GHSA-X5J2-G63M-F8G4 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk.

Q: What actually determines whether GHSA-X5J2-G63M-F8G4 is exploitable, and how bad it is?

Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.

Summary

pqc_kyber KyberSlash: division timings depending on secrets

Various Kyber software libraries in various environments leak secret information into timing, specifically because

these libraries include a line of code that divides a secret numerator by a public denominator,
the number of CPU cycles for division in various environments varies depending on the inputs to the division, and
this variation appears within the range of numerators used in these libraries.

The KyberSlash pages track which Kyber libraries have this issue, and include a FAQ about the issue.

Author

The KyberSlash pages were written by Daniel J. Bernstein. The FAQ originally said "I", but some people seemed to have trouble finding this authorship statement, so the FAQ now says "Bernstein" instead.

URL

The permanent link for the KyberSlash pages is https://kyberslash.cr.yp.to.

Mitigation status in pqc_kyber crate

The issues has not been resolved in the pqc_kyber crate. A third-party fork that mitigates this attack vector has been published as safe_pqc_kyber.

Impact

GHSA-X5J2-G63M-F8G4 has a CVSS score of 7.4 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. No fixed version is listed yet, so configuration controls and monitoring matter more in the interim.

Affected versions

pqc_kyber (<= 0.7.1)

Security releases

Not available

Kodem intelligence

Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.

Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.

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Remediation advice

No fixed version is listed for GHSA-X5J2-G63M-F8G4 yet.

Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.

Frequently Asked Questions

What is GHSA-X5J2-G63M-F8G4? GHSA-X5J2-G63M-F8G4 is a high-severity security vulnerability in pqc_kyber (rust), affecting versions <= 0.7.1. No fixed version is listed yet.
How severe is GHSA-X5J2-G63M-F8G4? GHSA-X5J2-G63M-F8G4 has a CVSS score of 7.4 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
Which versions of pqc_kyber are affected by GHSA-X5J2-G63M-F8G4? pqc_kyber (rust) versions <= 0.7.1 is affected.
Is there a fix for GHSA-X5J2-G63M-F8G4? No fixed version is listed for GHSA-X5J2-G63M-F8G4 yet. Monitor the advisory for updates and apply mitigations in the interim.
Is GHSA-X5J2-G63M-F8G4 exploitable, and should I be worried? Whether GHSA-X5J2-G63M-F8G4 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
What actually determines whether GHSA-X5J2-G63M-F8G4 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.