# CVE-2026-17347: pgAdmin 4: OS command injection in MASTER_PASSWORD_HOOK via untrusted username substitution

> Authenticated users can execute arbitrary OS commands via shell metacharacters in usernames when the MASTER_PASSWORD_HOOK feature is enabled.

- **Severity:** High 7.7 (`CVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 31 Jul 2026
- **Updated:** 1 Aug 2026
- **Also known as:** GHSA-f649-fjv9-qgcg

## What is CVE-2026-17347?

CVE-2026-17347 is a high-severity command injection vulnerability in pgadmin.org pgAdmin 4, published on 31 Jul 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

The MASTER_PASSWORD_HOOK setting, introduced in pgAdmin 4 7.2, lets an administrator configure an external command that returns a per-user encryption key, with %u in the configured string replaced by the current user's name. The previous implementation substituted the username directly into the command string and executed the result with subprocess.Popen(..., shell=True). Because the username can originate from an external authentication source (OAuth/OIDC claims, Kerberos, webserver auth) rather than a value pgAdmin fully controls, a username containing shell metacharacters (';', '$()', backticks, pipes, '&&', newlines) allowed an authenticated user to execute arbitrary commands as the pgAdmin service account in any deployment where the configured hook string uses %u.

Fix tokenises the trusted, administrator-configured hook string into an argument vector first (using shlex in POSIX-quoting mode, with backslash-escaping disabled so Windows-style paths are not mis-parsed), substitutes the untrusted username into the individual argv elements, and executes with shell=False. The username is therefore always confined to a single argv element; any shell metacharacters it contains are inert. Administrators whose MASTER_PASSWORD_HOOK previously relied on shell features (pipes, redirection, environment-variable expansion, globbing) within the hook string itself must move that logic into the invoked script, since it is no longer interpreted by a shell.

This issue affects pgAdmin 4: from 7.2 before 9.17.

Weakness: CWE-88 (Improper Neutralization of Argument Delimiters in a Command), CWE-78 (Improper Neutralization of Special Elements used in an OS Command)

## Which versions are affected by CVE-2026-17347?

It affects 1 product.


Products: Pgadmin Pgadmin 4.

## How do I fix CVE-2026-17347?

Upgrade to a fixed version.

## Is CVE-2026-17347 being exploited?

There is no known exploitation of CVE-2026-17347 in the wild and no public exploit code.

## Other vulnerabilities in pgadmin.org pgAdmin 4

- [CVE-2025-2945](https://insights.sbomify.com/CVE-2025-2945/): pgAdmin 4: Remote Code Execution in Query Tool and Cloud Deployment (critical 9.9)
- [CVE-2024-9014](https://insights.sbomify.com/CVE-2024-9014/): OAuth2 client id and secret exposed through the web browser in pgAdmin 4 (critical 9.9)
- [CVE-2026-12046](https://insights.sbomify.com/CVE-2026-12046/): Deserialization in pgAdmin 4 (critical 9.5)
- [CVE-2026-17351](https://insights.sbomify.com/CVE-2026-17351/): SQL injection in pgAdmin 4 (critical 9.4)
- [CVE-2026-17566](https://insights.sbomify.com/CVE-2026-17566/): Command injection in pgAdmin 4 (critical 9.4)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-17347 and fix it if it is affected.

What it is: CVE-2026-17347 is a high-severity command injection vulnerability in pgadmin.org pgAdmin 4, published on 31 Jul 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-17347 in the wild and no public exploit code.

Affected product: pgadmin.org pgAdmin 4. 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-2026-17347/ (Markdown: https://insights.sbomify.com/CVE-2026-17347/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-17347
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-17347
- OSV: https://osv.dev/vulnerability/CVE-2026-17347

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-17347/
Summaries are generated and may contain mistakes; the official description above is the record.