# CVE-2026-87913: Missing S3 bucket ownership verification in the AWS Security Agent MCP server

> Attackers can steal private source archives and credentials by exploiting missing S3 bucket ownership checks in the AWS Security Agent MCP server.

- **Severity:** Medium 5.1 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:N/SC:H/SI:L/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 10 Sep 2026
- **Updated:** 10 Sep 2026

## What is CVE-2026-87913?

CVE-2026-87913 is a medium-severity missing authorization vulnerability in AWS Security Agent MCP server, published on 10 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

A missing S3 bucket ownership verification in the AWS Security Agent MCP server before 0.2.0 version might allow remote attackers to obtain the private source archive of a scanned workspace, including credentials and infrastructure state contained in that archive, via a pre-registered storage bucket whose name is derived from a publicly known account identifier.

To remediate this issue, users should upgrade to version 0.2.0. Users should also verify that the scan output bucket in their account is owned by their own account, because upgrading does not release a bucket name that a third party has already registered.

Weakness: CWE-341 (Predictable from Observable State), CWE-283 (Unverified Ownership)

## Which versions are affected by CVE-2026-87913?


## How do I fix CVE-2026-87913?

No fix has been published for CVE-2026-87913 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-87913 being exploited?

There is no known exploitation of CVE-2026-87913 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-87913 and fix it if it is affected.

What it is: CVE-2026-87913 is a medium-severity missing authorization vulnerability in AWS Security Agent MCP server, published on 10 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-87913 in the wild and no public exploit code.

Affected product: AWS Security Agent MCP server. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2026-87913/ (Markdown: https://insights.sbomify.com/CVE-2026-87913/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-87913
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-87913
- OSV: https://osv.dev/vulnerability/CVE-2026-87913

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-87913/
Summaries are generated and may contain mistakes; the official description above is the record.