# CVE-2026-12957 — Amazon Web Services Language Servers for AWS

> As of 2026-06-23, CVE-2026-12957 is a HIGH-severity vulnerability in Amazon Web Services Language Servers for AWS, CVSS v3.1 7.8, EPSS 0.1% (2.0th percentile). Threadlinqs Intelligence links 1 tracked threat campaign to CVE-2026-12957, most recently “Amazon Q Developer Extension Trust-Boundary & Symlink Flaws (CVE-2026-12957, CVE-2026-12958) Auto-Execute Malicious MCP Configs”.

**Last updated:** 2026-06-23

## What is CVE-2026-12957?

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.

The record classifies CVE-2026-12957 under weakness class [CWE-732](https://intel.threadlinqs.com/cwe/CWE-732). Its CVSS v3 base vector states that the flaw requires local access to the host, needs no prior authentication, needs a user to take an action first, and has high impact on confidentiality, integrity, availability. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 104 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 7.8 — HIGH (`CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H`)
- **CVSS v4.0 base score:** 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`)
- **EPSS (FIRST):** 0.1% probability of exploitation in the next 30 days, higher than 2.0% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 4/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-06-23

## Is CVE-2026-12957 being exploited?

No public exploitation evidence for CVE-2026-12957 is recorded in the sources Threadlinqs tracks — CISA KEV, Exploit-DB, public proof-of-concept repositories and ProjectDiscovery Nuclei — as of 2026-06-23. That is an absence of evidence in those feeds, not a guarantee that the vulnerability is unexploited.

## Affected products and versions

- **Amazon Web Services**: Language Servers for AWS

## How to fix CVE-2026-12957

No vendor patch reference has been recorded for CVE-2026-12957 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-12957

1 tracked threat in the Threadlinqs corpus references CVE-2026-12957, either in the campaign’s CVE list or as an indicator on the campaign record.

- [Amazon Q Developer Extension Trust-Boundary & Symlink Flaws (CVE-2026-12957, CVE-2026-12958) Auto-Execute Malicious MCP Configs](https://intel.threadlinqs.com/threat/TL-2026-0950) — HIGH · 2026-06-26

## Sources

Enriched from CVE.org, NVD, FIRST EPSS. Last verified by Threadlinqs on 2026-06-27. This product uses the NVD API but is not endorsed or certified by the NVD.

**Vendor advisory and patch**

- [aws.amazon.com — vendor advisory](https://aws.amazon.com/security/security-bulletins/2026-047-aws/)

**Third-party advisory**

- [github.com — third party advisory](https://github.com/aws/language-servers/security/advisories/GHSA-xhcr-j4j9-3gh7)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-12957
Full detection coverage and IOCs for threats exploiting CVE-2026-12957 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp