How severe is GHSA-x5j2-g63m-f8g4?

GHSA-x5j2-g63m-f8g4 has a CVSS score of 7.4/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by GHSA-x5j2-g63m-f8g4?

GHSA-x5j2-g63m-f8g4 affects the following packages: pqc_kyber (crates.io). Ecosystems affected: crates.io.

How do I fix GHSA-x5j2-g63m-f8g4?

The records we use list no patched version of pqc_kyber for GHSA-x5j2-g63m-f8g4. Check the maintainer's advisory, and where your build allows, override or pin the dependency away from the vulnerable range.

How do I detect GHSA-x5j2-g63m-f8g4 in my crates.io dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for pqc_kyber, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate GHSA-x5j2-g63m-f8g4 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.

Is GHSA-x5j2-g63m-f8g4 actively exploited in the wild?

No public exploit code has been indexed for GHSA-x5j2-g63m-f8g4 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

When was GHSA-x5j2-g63m-f8g4 published, and has it been updated?

GHSA-x5j2-g63m-f8g4 was published on February 9, 2024 and was last updated on April 15, 2024. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🦀

🦀 crates.io

Not in CISA KEV

HIGH severity

pqc_kyber KyberSlash: division timings depending on secretsGHSA-x5j2-g63m-f8g4

HIGHFix: bwesterb/argyle-kyber@b5c6ad1

GHSA-x5j2-g63m-f8g4 is a high-severity (CVSS 7.4) vulnerability in pqc_kyber. The records list no fixed version yet; check the vendor advisory below and apply the mitigations in the meantime.

Also known asRUSTSEC-2023-0079

Published

Feb 9, 2024

Updated

Apr 15, 2024

Affected

1 pkg

Patched

See advisory

Exploits

None indexed

Exploitation data as of Apr 15, 2024 · OSV.dev, FIRST.org (EPSS)

Real-World Exposure

1 pkg affected

🦀pqc_kyber

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.

Description

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.

Affected Packages

1 total

Ecosystem	Package	Vulnerable range	Fix
🦀crates.io	`pqc_kyber`	all versions	No fix

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for pqc_kyber, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Remediation status
The records we use list no patched version of pqc_kyber for GHSA-x5j2-g63m-f8g4. Check the maintainer's advisory, and where your build allows, override or pin the dependency away from the vulnerable range.
Mitigate without a patch
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.

Frequently Asked Questions

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](https://kyberslash.cr.yp.to/libraries.html) have this issue, and include a [FAQ](https://kyberslash.cr.yp.to/faq.html) about the issue

O3 Security · Impact-Aware SCA

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