# CVE-2021-26728: spx_restservice KillDupUsr_func Command Injection and Stack-Based Buffer Overflow

> Attackers can execute arbitrary code with root privileges via command injection and buffer overflow in the spx_restservice component.

- **Severity:** Critical 10.0 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/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:** 24 Oct 2022
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-4pjq-m8x4-557r

## What is CVE-2021-26728?

CVE-2021-26728 is a critical command injection vulnerability in Lanner Inc IAC-AST2500A, published on 24 Oct 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Command injection and stack-based buffer overflow vulnerabilities in the KillDupUsr_func function of spx_restservice allow an attacker to execute arbitrary code with the same privileges as the server user (root). This issue affects: Lanner Inc IAC-AST2500A standard firmware version 1.10.0.

Weakness: CWE-787 (Out-of-bounds Write), CWE-77 (Improper Neutralization of Special Elements used in a Command), CWE-94 (Improper Control of Generation of Code), CWE-121 (Stack-based Buffer Overflow)

## Which versions are affected by CVE-2021-26728?

It affects 1 product.


Products: Lannerinc Iac-Ast2500a Firmware.

## How do I fix CVE-2021-26728?

No fix has been published for CVE-2021-26728 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-26728 being exploited?

There is no known exploitation of CVE-2021-26728 in the wild and no public exploit code.

## Other vulnerabilities in Lanner Inc IAC-AST2500A

- [CVE-2021-26727](https://insights.sbomify.com/CVE-2021-26727/): spx_restservice SubNet_handler_func Multiple Command Injections and Stack-Based Buffer Overflows (critical 10.0)
- [CVE-2021-26729](https://insights.sbomify.com/CVE-2021-26729/): spx_restservice Login_handler_func Command Injection and Multiple Stack-Based Buffer Overflows (critical 10.0)
- [CVE-2021-26730](https://insights.sbomify.com/CVE-2021-26730/): spx_restservice Login_handler_func Subfunction Stack-Based Buffer Overflow (critical 10.0)
- [CVE-2021-26731](https://insights.sbomify.com/CVE-2021-26731/): spx_restservice modifyUserb_func Command Injection and Multiple Stack-Based Buffer Overflows (critical 9.1)
- [CVE-2021-26732](https://insights.sbomify.com/CVE-2021-26732/): spx_restservice First_network_func Broken Access Control (medium 6.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-26728 and fix it if it is affected.

What it is: CVE-2021-26728 is a critical command injection vulnerability in Lanner Inc IAC-AST2500A, published on 24 Oct 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-26728 in the wild and no public exploit code.

Affected product: Lanner Inc IAC-AST2500A. 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-2021-26728/ (Markdown: https://insights.sbomify.com/CVE-2021-26728/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-26728
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-26728
- OSV: https://osv.dev/vulnerability/CVE-2021-26728

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-26728/
Summaries are generated and may contain mistakes; the official description above is the record.