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High, CVSS 8.1amended

Kysely has a MySQL SQL Injection via Backslash Escape Bypass in non-type-safe usage of JSON path keys.

CVE-2026-33442GHSA-fr9j-6mvq-frcv

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (kysely 0.28.14), 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

  • npm kysely

    Affected
    >= 0.28.12, <= 0.28.13
    Fixed in
    0.28.14

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
8.1 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS
  • CVE-2026-33442: 0.45% estimated exploitation activity in the next 30 days; percentile 39.13 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary The sanitizeStringLiteral method in Kysely's query compiler escapes single quotes (' → '') but does not escape backslashes. On MySQL with the default BACKSLASHESCAPES SQL mode, an attacker can inject a backslash before a single quote to neutralize the escaping, breaking out of the JSON path string literal and injecting arbitrary SQL. Details When a user calls .key(value) on a JSON path builder, the value flows through: 1. JSONPathBuilder.key(key) at src/query-builder/json-path-builder.ts:166 stores the key as a JSONPathLegNode with type 'Member'. 2. During compilation, DefaultQueryCompiler.visitJSONPath() at src/query-compiler/default-query-compiler.ts:1609 wraps the full path in single quotes ('$...'). 3. DefaultQueryCompiler.visitJSONPathLeg() at src/query-compiler/default-query-compiler.ts:1623 calls sanitizeStringLiteral(node.value) for string values (line 1630). 4. sanitizeStringLiteral() at src/query-compiler/default-query-compiler.ts:1819-1821 only doubles single…

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

    Amended from ghsa record GHSA-fr9j-6mvq-frcv

  2. Revision 1 · created ·

    Published from osv record GHSA-fr9j-6mvq-frcv

Agent brief

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# Patch Next advisory brief: CVE-2026-33442

Advisory: Kysely has a MySQL SQL Injection via Backslash Escape Bypass in non-type-safe usage of JSON path keys.
IDs: CVE-2026-33442, GHSA-fr9j-6mvq-frcv
Record: https://patchnext.com/advisories/cve-2026-33442 (revision 2, source checked 26 Oct 2026, 12:47 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: kysely 0.28.14. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm kysely: affected >= 0.28.12, <= 0.28.13; fixed in 0.28.14

## Suggested inspection (read-only)
- `npm ls kysely --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## 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 kysely.
- 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-fr9j-6mvq-frcv (OSV record GHSA-fr9j-6mvq-frcv lists affected ranges: npm kysely >=0.28.12 <0.28.14 (fixed))
- Verified: https://github.com/advisories/GHSA-fr9j-6mvq-frcv (GitHub-reviewed advisory GHSA-fr9j-6mvq-frcv lists affected ranges: npm kysely >=0.28.12 <=0.28.13)

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