# CVE-2026-111103: HTTP/2 StreamError recovery rolls back connection state and bypasses per-connection limits in Bandit


- **Severity:** High 8.2 (`CVSS:4.0/AV:N/AC:L/AT:P/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-2026-111103, GHSA-2238-pgfc-w82m, UBUNTU-CVE-2026-111103

## What is CVE-2026-111103?

CVE-2026-111103 is a high-severity vulnerability in mtrudel bandit, published on 26 Oct 2026. 

### Official description

Improper Cleanup on Thrown Exception vulnerability in the HTTP/2 handler of mtrudel bandit allows an unauthenticated remote attacker to bypass per-connection resource limits via a single TCP write that carries several frames, one of which raises a stream error.

When a frame raises StreamError partway through a chunk, Bandit.HTTP2.Handler.handle_data/3 sends RST_STREAM and continues with the connection state from before the chunk, dropping the rest of it. Streams opened by earlier frames in the chunk keep running their Plug calls, but the stream counts, last_stream_id, the rapid-reset timestamps, the HPACK decoder state and the buffer roll back, so max_concurrent_streams, max_requests and the rapid-reset limiter never see those streams. A client that sends one HEADERS frame more than max_concurrent_streams in each write has the extra refused and the others forgotten: with a limit of 10, five such writes run 50 Plug calls at once.

This issue affects bandit: from 1.9.0 before 1.14.0.

Weakness: CWE-460 (Improper Cleanup on Thrown Exception)

## Which versions are affected by CVE-2026-111103?

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


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `bandit` | Hex | From 1.9.0 | 1.14.0 |

## How do I fix CVE-2026-111103?

Upgrade bandit to 1.14.0 or later.

## Is CVE-2026-111103 being exploited?

There is no known exploitation of CVE-2026-111103 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-111103 and fix it if it is affected.

What it is: CVE-2026-111103 is a high-severity vulnerability in mtrudel bandit, published on 26 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-111103 in the wild and no public exploit code.

Affected packages and fixed versions:
- bandit (Hex): affected from 1.9.0; 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-2026-111103/ (Markdown: https://insights.sbomify.com/CVE-2026-111103/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-111103
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-111103
- OSV: https://osv.dev/vulnerability/CVE-2026-111103

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-111103/
Summaries are generated and may contain mistakes; the official description above is the record.