# CVE-2026-55798: Pillow: WindowsViewer.get_command() OS command injection via unescaped shell path

> An attacker can execute arbitrary commands on Windows systems by providing a malicious file path to the Pillow library's viewer function.

- **Severity:** Medium 4.5 (`CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 6 Jul 2026
- **Updated:** 7 Jul 2026
- **Also known as:** BIT-pillow-2026-55798, CLSA-2026-1787903381, CLSA-2026-1788345043, CLSA-2026-1788863918, ECHO-c51d-efb4-9117, GHSA-4x4j-2g7c-83w6, MINI-2mvj-hjgh-cghg, MINI-37f4-cw5j-p2pv, MINI-4rpv-px28-3c7v, MINI-52xm-2xhj-6c7h, MINI-7m97-pqmc-5m43, MINI-7q39-4535-95j5, MINI-7ww4-2prv-77w7, MINI-858q-7464-r54c, MINI-8xg3-mv56-6jq3, MINI-q45r-gmp7-425r, MINI-v7v2-m8vr-66gw, PYSEC-2026-2257

## What is CVE-2026-55798?

CVE-2026-55798 is a medium-severity command injection vulnerability in Python Pillow, published on 6 Jul 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

Pillow is a Python imaging library. Prior to 12.3.0, WindowsViewer.get_command() constructed a cmd.exe shell command by directly embedding a file path into an f-string without escaping and passed the result to subprocess.Popen(..., shell=True), allowing shell metacharacters in the file path to inject arbitrary cmd.exe commands. This issue is fixed in version 12.3.0.

Weakness: CWE-78 (Improper Neutralization of Special Elements used in an OS Command)

## Which versions are affected by CVE-2026-55798?

4 open source packages ship an affected version, including pillow and Pillow. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `pillow` | Bitnami | All versions | 12.3.0 |
| `pillow` | PyPI | All versions | 12.3.0 |
| `pillow` | PyPI | All versions | 12.3.0 |
| `Pillow` | PyPI | All versions | 12.3.0 |

Products: Python Pillow.

## How do I fix CVE-2026-55798?

Upgrade pillow to 12.3.0 or later.

## Is CVE-2026-55798 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-55798 exists.

## Other vulnerabilities in Python Pillow

- [CVE-2014-3007](https://insights.sbomify.com/CVE-2014-3007/): Pillow command injection (critical 10.0)
- [CVE-2026-96639](https://insights.sbomify.com/CVE-2026-96639/): Pillow multi-frame loaders can reuse stale native image storage after mode transitions (critical 9.8)
- [CVE-2022-30595](https://insights.sbomify.com/CVE-2022-30595/): Buffer over-flow in Pillow (critical 9.8)
- [CVE-2021-25289](https://insights.sbomify.com/CVE-2021-25289/): Out of bounds write in Pillow (critical 9.8)
- [CVE-2016-4009](https://insights.sbomify.com/CVE-2016-4009/): Pillow Integer overflow in ImagingResampleHorizontal (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-55798 and fix it if it is affected.

What it is: CVE-2026-55798 is a medium-severity command injection vulnerability in Python Pillow, published on 6 Jul 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-55798 exists.

Affected packages and fixed versions:
- pillow (Bitnami): affected all versions; fixed in 12.3.0
- pillow (PyPI): affected all versions; fixed in 12.3.0
- pillow (PyPI): affected all versions; fixed in 12.3.0
- Pillow (PyPI): affected all versions; fixed in 12.3.0

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-2026-55798/ (Markdown: https://insights.sbomify.com/CVE-2026-55798/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-55798
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-55798
- OSV: https://osv.dev/vulnerability/CVE-2026-55798

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-55798/
Summaries are generated and may contain mistakes; the official description above is the record.