# CVE-2026-114213: WebSocket 1-byte continuation frames bypass `max_fragmented_message_size` in Bandit


- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 26 Oct 2026
- **Updated:** 26 Oct 2026
- **Also known as:** EEF-CVE-2026-114213, GHSA-cpx7-qf6w-jc63, UBUNTU-CVE-2026-114213

## What is CVE-2026-114213?

CVE-2026-114213 is a high-severity vulnerability in mtrudel bandit, published on 26 Oct 2026. 

### Official description

Allocation of Resources Without Limits or Throttling vulnerability in the WebSocket fragment reassembly of mtrudel bandit allows an unauthenticated remote attacker to exhaust server memory via a fragmented message made of many 1-byte continuation frames.

Bandit.WebSocket.Connection checks max_fragmented_message_size against the payload bytes received, but keeps every non-final continuation frame as a new list cell around its own binary, and nothing limits the number of fragments. A 1-byte fragment costs 7 bytes on the wire but about 150 to 170 bytes of server memory, so one connection can hold about 150 times the configured limit, roughly 1.2 to 1.4 GB at the default 8 MB. Ping frames between fragments keep the connection alive past the idle timeout.

This issue affects bandit: from 1.11.0 before 1.14.0.

Weakness: CWE-770 (Allocation of Resources Without Limits or Throttling)

## Which versions are affected by CVE-2026-114213?

1 open source package ship an affected version, including bandit.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `bandit` | Hex | From 1.11.0 | 1.14.0 |

## How do I fix CVE-2026-114213?

Upgrade bandit to 1.14.0 or later.

## Is CVE-2026-114213 being exploited?

There is no known exploitation of CVE-2026-114213 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-114213 and fix it if it is affected.

What it is: CVE-2026-114213 is a high-severity vulnerability in mtrudel bandit, published on 26 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-114213 in the wild and no public exploit code.

Affected packages and fixed versions:
- bandit (Hex): affected from 1.11.0; fixed in 1.14.0

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-2026-114213/ (Markdown: https://insights.sbomify.com/CVE-2026-114213/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-114213
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-114213
- OSV: https://osv.dev/vulnerability/CVE-2026-114213

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-114213/
Summaries are generated and may contain mistakes; the official description above is the record.