# CVE-2026-123534: Tornado before 6.6 Path Traversal via static_url() Version Hashing


- **Severity:** High 8.3 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 8 Nov 2026
- **Updated:** 9 Nov 2026
- **Also known as:** AZL-113104, CLEANSTART-2026-ZF35856, DEBIAN-CVE-2026-123534, GHSA-v8g8-cp5j-42fg, GHSA-xc53-2vgx-jv3x, UBUNTU-CVE-2026-123534

## What is CVE-2026-123534?

CVE-2026-123534 is a high-severity vulnerability in tornadoweb tornado, published on 8 Nov 2026. 

### Official description

Tornado before 6.6 contains a path traversal vulnerability in RequestHandler.static_url() and get_version() that allows attackers to hash files outside static_path using ../ sequences. Attackers controlling input passed to static_url() can obtain SHA-512 hashes of readable files to confirm their existence, or reference /dev/zero to block the event loop indefinitely.

Weakness: CWE-22 (Improper Limitation of a Pathname to a Restricted Directory)

## Which versions are affected by CVE-2026-123534?


## How do I fix CVE-2026-123534?

Upgrade to a fixed version.

## Is CVE-2026-123534 being exploited?

There is no known exploitation of CVE-2026-123534 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-123534 and fix it if it is affected.

What it is: CVE-2026-123534 is a high-severity vulnerability in tornadoweb tornado, published on 8 Nov 2026. 
Exploitation: There is no known exploitation of CVE-2026-123534 in the wild and no public exploit code.

Affected product: tornadoweb tornado. 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-2026-123534/ (Markdown: https://insights.sbomify.com/CVE-2026-123534/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-123534
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-123534
- OSV: https://osv.dev/vulnerability/CVE-2026-123534

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-123534/
Summaries are generated and may contain mistakes; the official description above is the record.