# CVE-2026-105811: Authorization bypass through a user-controlled key in the Amazon Q Business Lambda hook sample in QnABot on AWS

> Authenticated users can read arbitrary S3 objects via a user-controlled key in the optional Amazon Q Business Lambda hook sample.

- **Severity:** High 7.1 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 6 Oct 2026
- **Updated:** 7 Oct 2026
- **Also known as:** GHSA-r223-2773-wq4w

## What is CVE-2026-105811?

CVE-2026-105811 is a high-severity missing authorization vulnerability in qnabot-on-aws, published on 6 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Authorization bypass through a user-controlled key in the optional Amazon Q Business Lambda hook sample ( q-business-lambda-hook https://github.com/aws-solutions-library-samples/qnabot-on-aws/blob/main/source/docs/lambda_hooks/README.md ), available with QnABot on AWS versions 7.0.0 through 7.4.5, might allow an authenticated remote user to read arbitrary Amazon S3 objects in the deploying AWS account. This sample solution provides an example Lambda hook and requires separate, manual deployment and additional setup. It is not deployed automatically with QnABot. Customers who have not deployed this optional sample hook are not affected and do not need to take action. 

To remediate this issue, affected customers should update the QnABot on AWS stack to version 7.4.6 or later and then redeploy the Amazon Q Business Lambda hook sample stack. Updating the QnABot on AWS stack alone does not deliver the fix.

Weakness: CWE-639 (Authorization Bypass Through User-Controlled Key)

## Which versions are affected by CVE-2026-105811?


## How do I fix CVE-2026-105811?

No fix has been published for CVE-2026-105811 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-105811 being exploited?

There is no known exploitation of CVE-2026-105811 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-105811 and fix it if it is affected.

What it is: CVE-2026-105811 is a high-severity missing authorization vulnerability in qnabot-on-aws, published on 6 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-105811 in the wild and no public exploit code.

Affected product: qnabot-on-aws. 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-2026-105811/ (Markdown: https://insights.sbomify.com/CVE-2026-105811/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-105811
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-105811
- OSV: https://osv.dev/vulnerability/CVE-2026-105811

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-105811/
Summaries are generated and may contain mistakes; the official description above is the record.