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High, CVSS 7.8amended

Observable Timing Discrepancy in pypqc

GHSA-hvh4-5qr6-3v7r

What to do

Vendor response not established. Follow the primary source's mitigation guidance and check back for a fix.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • PyPI pypqc

    Affected
    >= 0.0.4, <= 0.0.6.2
    Fixed in
    no fixed version recorded

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
7.8 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N/E:P/RL:U/RC:C
EPSS
No dated EPSS signal available.
Source description

As published by the source; long descriptions are shortened.

Impact kyber512, kyber768, and kyber1024 on Mac OS \(or when compiled with clang\) only: An attacker able to submit many decapsulation requests against a single private key, and to gain timing information about the decapsulation, could recover the private key. Proof-of-concept exploit exists for a local attacker. CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N/E:P/RL:U/RC:C Patches No patch is currently available / pending upstream PQClean#556. Workarounds No workarounds have been reported. The 0.0.7 - 0.0.7.1 upgrade, when available, should be a drop-in replacement<!--; it has no known breaking changes--. References https://pqshield.com/pqshield-plugs-timing-leaks-in-kyber-ml-kem-to-improve-pqc-implementation-maturity/ https://github.com/antoonpurnal/clangover https://www.github.com/PQClean/PQClean/issues/556 https://www.github.com/pq-crystals/kyber/commit/9b8d30698a3e7449aeb34e62339d4176f11e3c6c

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 2 · amended ·

    Amended from ghsa record GHSA-hvh4-5qr6-3v7r

  2. Revision 1 · created ·

    Published from osv record GHSA-hvh4-5qr6-3v7r

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: GHSA-hvh4-5qr6-3v7r

Advisory: Observable Timing Discrepancy in pypqc
IDs: GHSA-hvh4-5qr6-3v7r
Record: https://patchnext.com/advisories/ghsa-hvh4-5qr6-3v7r (revision 2, source checked 26 Oct 2026, 13:16 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI pypqc: affected >= 0.0.4, <= 0.0.6.2

## Suggested inspection (read-only)
- `python -m pip show pypqc`: prints the installed version. Run with the environment that serves production active.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on pypqc.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-hvh4-5qr6-3v7r (OSV record GHSA-hvh4-5qr6-3v7r lists affected ranges: PyPI pypqc >=0.0.4 <=0.0.6.2)
- Verified: https://github.com/advisories/GHSA-hvh4-5qr6-3v7r (GitHub-reviewed advisory GHSA-hvh4-5qr6-3v7r lists affected ranges: PyPI pypqc >=0.0.4 <=0.0.6.2)

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