# CVE-2026-6855: Instructlab: instructlab: path traversal allows arbitrary directory creation and file write

> A local attacker can exploit a path traversal flaw in InstructLab to create directories and write files to arbitrary locations, leading to unauthorized data modification or disclosure.

- **Severity:** High 7.1 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 22 Apr 2026
- **Updated:** 24 Apr 2026
- **Also known as:** GHSA-pqmg-c2j8-fq92, PYSEC-2026-2521

## What is CVE-2026-6855?

CVE-2026-6855 is a high-severity path traversal vulnerability in Red Hat Enterprise Linux AI (RHEL AI) 3, published on 22 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A flaw was found in InstructLab. A local attacker could exploit a path traversal vulnerability in the chat session handler by manipulating the `logs_dir` parameter. This allows the attacker to create new directories and write files to arbitrary locations on the system, potentially leading to unauthorized data modification or disclosure.

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

## Which versions are affected by CVE-2026-6855?

3 open source packages ship an affected version, including instructlab. It affects 2 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `instructlab` | PyPI | All versions to 0.26.1 | None |
| `instructlab` | PyPI | All versions to 0.26.1 | None |
| `instructlab` | PyPI | All versions to 0.26.1 | None |

Products: Redhat Enterprise Linux Ai, Redhat Instructlab.

## How do I fix CVE-2026-6855?

No fix has been published for CVE-2026-6855 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-6855 being exploited?

There is no known exploitation of CVE-2026-6855 in the wild and no public exploit code.

## Other vulnerabilities in Red Hat Enterprise Linux AI (RHEL AI) 3

- [CVE-2026-6859](https://insights.sbomify.com/CVE-2026-6859/): Instructlab: instructlab: arbitrary code execution due to hardcoded `trust_remote_code=true` (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-6855 and fix it if it is affected.

What it is: CVE-2026-6855 is a high-severity path traversal vulnerability in Red Hat Enterprise Linux AI (RHEL AI) 3, published on 22 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-6855 in the wild and no public exploit code.

Affected packages and fixed versions:
- instructlab (PyPI): affected all versions up to 0.26.1; no fix listed
- instructlab (PyPI): affected all versions up to 0.26.1; no fix listed
- instructlab (PyPI): affected all versions up to 0.26.1; no fix listed

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-2026-6855/ (Markdown: https://insights.sbomify.com/CVE-2026-6855/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-6855
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-6855
- OSV: https://osv.dev/vulnerability/CVE-2026-6855

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-6855/
Summaries are generated and may contain mistakes; the official description above is the record.