# CVE-2026-12957: Arbitrary Code Execution in Language Servers for AWS

> A local attacker can execute arbitrary code by tricking a user into opening a malicious workspace in AWS Language Servers.

- **Severity:** High 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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 23 Jun 2026
- **Updated:** 23 Jun 2026
- **Also known as:** GHSA-xhcr-j4j9-3gh7

## What is CVE-2026-12957?

CVE-2026-12957 is a high-severity code injection vulnerability in Amazon Web Services Language Servers for AWS, published on 23 Jun 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

Improper trust boundary enforcement in Language Servers for AWS before version 1.65.0 on all supported platforms may allow a for arbitrary code execution. If a local user opens a maliciously crafted workspace, any commands within the project configuration files may be automatically executed. This issue requires the user to trust the workspace when prompted.

To remediate this issue, users should upgrade to Language Servers for AWS version 1.65.0 or higher.

Weakness: CWE-732 (Incorrect Permission Assignment for Critical Resource)

## Which versions are affected by CVE-2026-12957?

2 open source packages ship an affected version, including @aws/lsp-codewhisperer.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `@aws/lsp-codewhisperer` | npm | All versions | 0.0.113 |
| `@aws/lsp-codewhisperer` | npm | All versions | 0.0.113 |

## How do I fix CVE-2026-12957?

Upgrade @aws/lsp-codewhisperer to 0.0.113 or later.

## Is CVE-2026-12957 being exploited?

There is no known exploitation of CVE-2026-12957 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-12957 and fix it if it is affected.

What it is: CVE-2026-12957 is a high-severity code injection vulnerability in Amazon Web Services Language Servers for AWS, published on 23 Jun 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-12957 in the wild and no public exploit code.

Affected packages and fixed versions:
- @aws/lsp-codewhisperer (npm): affected all versions; fixed in 0.0.113
- @aws/lsp-codewhisperer (npm): affected all versions; fixed in 0.0.113

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-12957/ (Markdown: https://insights.sbomify.com/CVE-2026-12957/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-12957
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-12957
- OSV: https://osv.dev/vulnerability/CVE-2026-12957

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-12957/
Summaries are generated and may contain mistakes; the official description above is the record.