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Medium, CVSS 6.6

simd-json-derive vulnerable to MaybeUninit misuse

GHSA-pqpw-89w5-82v5

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (simd-json-derive 0.12.0), redeploy, then verify what is actually installed.

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

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS 4.0
6.6 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U · score source
EPSS
No dated EPSS signal available.
Source description

As published by the source; long descriptions are shortened.

An invalid use of MaybeUninit::uninit().assumeinit() in simd-json-derive's derive macro can cause undefined behavior. The original code used MaybeUninit to avoid initialisation of the struct and then set the fields using ptr::write. The undefined behavior triggered by this misuse of MaybeUninit can lead to invlaid memory access and panics in binaries compiled in release mode (aka simd-json-derive prior to version 0.12 has UB and optimizes into some nonsense) The version 0.12.0 removes this section of code, avoiding the use of MaybeUninit alltogether.

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

    Published from ghsa record GHSA-pqpw-89w5-82v5

Agent brief

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# Patch Next advisory brief: GHSA-pqpw-89w5-82v5

Advisory: `simd-json-derive` vulnerable to `MaybeUninit` misuse
IDs: GHSA-pqpw-89w5-82v5
Record: https://patchnext.com/advisories/ghsa-pqpw-89w5-82v5 (revision 1, source checked 26 Oct 2026, 15:38 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.6)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: simd-json-derive 0.12.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io simd-json-derive: affected < 0.12.0; fixed in 0.12.0

## Suggested inspection (read-only)
- crates.io simd-json-derive: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on simd-json-derive.
- 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://github.com/advisories/GHSA-pqpw-89w5-82v5 (GitHub-reviewed advisory GHSA-pqpw-89w5-82v5 lists affected ranges: crates.io simd-json-derive >=0 <0.12.0)

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