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High, CVSS 8.5amended

Language Servers for AWS Vulnerable to Arbitrary Code Execution

CVE-2026-12957GHSA-xhcr-j4j9-3gh7

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (@aws/lsp-codewhisperer 0.0.113), 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
8.5 · CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N · score source
EPSS
  • CVE-2026-12957: 0.23% estimated exploitation activity in the next 30 days; percentile 14.33 (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 Language Servers for AWS (the aws/language-servers project) provide the underlying language-server runtime that powers Amazon Q Developer's AI coding assistance across its IDE plugins (Visual Studio Code, JetBrains, Eclipse, and Visual Studio). Improper trust boundary enforcement in Language Servers for AWS may allow for arbitrary code execution. If a local user opens a maliciously crafted workspace, any commands within the project configuration files may be automatically executed. Impact When a local user opens a maliciously crafted workspace and trusts it when prompted, commands defined in the workspace's project-level configuration files may be executed automatically, resulting in arbitrary code execution on the user's host. This issue is triggered when a user opens a workspace, trusts it, and the agent subsequently executes commands defined in the project-level configuration files. Impacted versions: Language Servers for AWS version <1.65.0. Patches This issue has been…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 4 · amended ·

    Amended from ghsa record GHSA-xhcr-j4j9-3gh7

  2. Revision 3 · amended ·

    Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

  3. Revision 2 · amended ·

    Amended from osv record GHSA-xhcr-j4j9-3gh7

  4. Revision 1 · created ·

    Published from ghsa record GHSA-xhcr-j4j9-3gh7

Agent brief

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# Patch Next advisory brief: CVE-2026-12957

Advisory: Language Servers for AWS Vulnerable to Arbitrary Code Execution
IDs: CVE-2026-12957, GHSA-xhcr-j4j9-3gh7
Record: https://patchnext.com/advisories/cve-2026-12957 (revision 4, source checked 26 Oct 2026, 13:02 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: @aws/lsp-codewhisperer 0.0.113. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @aws/lsp-codewhisperer: affected < 0.0.113; fixed in 0.0.113

## Suggested inspection (read-only)
- `npm ls @aws/lsp-codewhisperer --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 @aws/lsp-codewhisperer.
- 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-xhcr-j4j9-3gh7 (GitHub-reviewed advisory GHSA-xhcr-j4j9-3gh7 lists affected ranges: npm @aws/lsp-codewhisperer >=0 <0.0.113)
- Verified: https://osv.dev/vulnerability/GHSA-xhcr-j4j9-3gh7 (OSV record GHSA-xhcr-j4j9-3gh7 lists affected ranges: npm @aws/lsp-codewhisperer >=0 <0.0.113 (fixed))

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