How severe is CVE-2026-12957?

No CVSS score has been assigned to CVE-2026-12957 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-12957?

CVE-2026-12957 affects the following packages: @aws/lsp-codewhisperer (npm). Ecosystems affected: npm.

How do I fix CVE-2026-12957?

Update @aws/lsp-codewhisperer to 0.0.113 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-12957 is resolved across your whole dependency graph.

How do I detect CVE-2026-12957 in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @aws/lsp-codewhisperer, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-12957 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is CVE-2026-12957 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-12957 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-12957?

CVE-2026-12957 has an EPSS (Exploit Prediction Scoring System) score of 0.2%, placing it in the 13th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-12957?

CVE-2026-12957 is classified as CWE-732 (CWE-732). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-12957 published, and has it been updated?

CVE-2026-12957 was published on June 23, 2026 and was last updated on October 21, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦 npm

Not in CISA KEV

CVE-2026-12957 — @aws/lsp-codewhisperer

Fix: Amazon-Q-Developer/language-servers#2708

CVE-2026-12957 is a CWE-732 vulnerability in @aws/lsp-codewhisperer. A fix is available for @aws/lsp-codewhisperer — see the affected versions and patch details below.

Arbitrary Code Execution in Language Servers for AWS

Also known asGHSA-xhcr-j4j9-3gh7

Published

Jun 23, 2026

Updated

Oct 21, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 20, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

A successful exploit gives an attacker total control of the affected component, not partial access.
CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-12957.

EPSS Exploitation Probability

via FIRST.org ↗

0.2%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs13th percentile — riskier than 13% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

1other npm packages depend on this — each one inherits the vulnerability until it's patched upstream

@aws/lsp-codewhisperernpm

259downloads / week

Description

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 addressed in Language Servers for AWS version 1.65.0. We recommend upgrading to the latest version and ensuring any forked or derivative code is patched to incorporate the new fixes.

Workarounds

No workarounds are available.

References

If you have any questions or comments about this advisory, AWS Security asks that you contact them via their vulnerability reporting page or directly via email to [email protected]. Please do not create a public GitHub issue.

Acknowledgement

AWS Security would like to thank Wiz and Maor Dokhanian for collaborating on this issue through the coordinated vulnerability disclosure process.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`@aws/lsp-codewhisperer`	all versions	0.0.113`npm install @aws/lsp-codewhisperer@0.0.113`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @aws/lsp-codewhisperer, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update @aws/lsp-codewhisperer to 0.0.113 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-12957 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

### 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, co

O3 Security · Impact-Aware SCA

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