How severe is CVE-2026-12958?

No CVSS score has been assigned to CVE-2026-12958 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-12958?

CVE-2026-12958 affects the following packages: @aws/lsp-codewhisperer (npm). Ecosystems affected: npm.

How do I fix CVE-2026-12958?

Update @aws/lsp-codewhisperer to 0.0.117 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-12958 is resolved across your whole dependency graph.

How do I detect CVE-2026-12958 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-2026-12958 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-2026-12958 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-12958 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-2026-12958?

CVE-2026-12958 has an EPSS (Exploit Prediction Scoring System) score of 0.2%, placing it in the 8th 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-2026-12958?

CVE-2026-12958 is classified as CWE-61 (CWE-61). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-12958 published, and has it been updated?

CVE-2026-12958 was published on June 23, 2026 and was last updated on August 16, 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-2026-12958 — @aws/lsp-codewhisperer

Fix: Amazon-Q-Developer/language-servers#2742

CVE-2026-12958 is a CWE-61 vulnerability in @aws/lsp-codewhisperer. A fix is available for @aws/lsp-codewhisperer — see the affected versions and patch details below.

Arbitrary file write in Language Servers for AWS

Also known asGHSA-6v3r-4p5c-mrp5

Published

Jun 23, 2026

Updated

Aug 16, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 9, 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-2026-12958.

EPSS Exploitation Probability

via FIRST.org ↗

0.2%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs8th percentile — riskier than 8% 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

647downloads / week

Description

Summary

Language Servers for AWS (the aws/language-servers project) provides the Language Server Protocol implementations that power AWS developer tooling, including the Amazon Q Developer agentic chat experience, across IDEs such as VS Code, JetBrains, Visual Studio, and Eclipse.

Missing symlink validation in Language Servers for AWS may allow an arbitrary file write outside of the workspace trust boundary. This may occur when a local user opens a workspace containing a maliciously crafted symlink that resolves to a file path outside the workspace trust boundary.

Impact

If a user opens a maliciously crafted workspace containing a symlink that resides within the workspace but resolves to a location outside the workspace trust boundary, the agent may follow that symlink and write to the external location without prompting the user for approval. This can result in the modification of files outside the intended workspace boundary.

This issue is triggered when a user opens a workspace, trusts it, and the agent subsequently writes to a path within that workspace.

Impacted versions: Language Servers for AWS version <1.69.0.

Patches

This issue has been addressed in AWS Language Servers version 1.69.0. 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 ask 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	0.0.117`npm install @aws/lsp-codewhisperer@0.0.117`

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 0.0.117 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-12958 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) provides the Language Server Protocol implementations that power AWS developer tooling, including the Amazon Q Developer agentic chat experience, across IDEs such as VS Code, JetBrains, Visual Studio, and Eclipse. Missing symlink validation in Language Servers for AWS may allow an arbitrary file write outside of the workspace trust boundary. This may occur when a local user opens a workspace containing a maliciously crafted symlink that resolves to a file path outside the workspace trust boundary. ## Impact If a user ope

O3 Security · Impact-Aware SCA

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