# CVE-2021-35211: SolarWinds Serv-U Remote Code Execution

> Remote attackers can exploit a memory corruption flaw in Serv-U to execute arbitrary code and gain privileged access to the host system.

- **Severity:** Critical 9.0 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H`)
- **Exploited in the wild:** Yes, since 3 Nov 2021 (CISA KEV), used in ransomware
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 14 Jul 2021
- **Updated:** 21 Oct 2025
- **Also known as:** GHSA-cpmg-9xq8-3934

## What is CVE-2021-35211?

CVE-2021-35211 is a critical memory corruption vulnerability in Solarwinds Serv-U, published on 14 Jul 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Microsoft discovered a remote code execution (RCE) vulnerability in the SolarWinds Serv-U product utilizing a Remote Memory Escape Vulnerability. If exploited, a threat actor may be able to gain privileged access to the machine hosting Serv-U Only. SolarWinds Serv-U Managed File Transfer and Serv-U Secure FTP for Windows before 15.2.3 HF2 are affected by this vulnerability.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2021-35211?

It affects 1 product.


Products: Solarwinds Serv-U.

## How do I fix CVE-2021-35211?

No fix has been published for CVE-2021-35211 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 17 Nov 2021.

## Is CVE-2021-35211 being exploited?

Yes. Attackers have exploited CVE-2021-35211 in the wild since at least 3 Nov 2021, including in ransomware campaigns.

Public exploit code:

- https://github.com/BishopFox/CVE-2021-35211 (github_poc): https://github.com/BishopFox/CVE-2021-35211
- Simple Serv-U CVE-2021-35211 PoC (github_poc): https://github.com/NattiSamson/Serv-U-CVE-2021-35211
- Serv-U-FTP CVE-2021-35211 exploit (github_poc): https://github.com/0xhaggis/CVE-2021-35211
- SolarWinds Serv-U FTP - Remote Code Execution (nuclei)

## Other vulnerabilities in Solarwinds Serv-U

- [CVE-2024-28995](https://insights.sbomify.com/CVE-2024-28995/): SolarWinds Serv-U Path Traversal Vulnerability (high 8.6, exploited in the wild)
- [CVE-2026-28318](https://insights.sbomify.com/CVE-2026-28318/): SolarWinds Serv-U Uncontrolled Resource Consumption (high 7.5, exploited in the wild)
- [CVE-2021-35247](https://insights.sbomify.com/CVE-2021-35247/): SolarWinds Serv-U Improper Input Validation (medium 4.3, exploited in the wild)
- [CVE-2020-35481](https://insights.sbomify.com/CVE-2020-35481/): Code injection in n/a (critical 9.8)
- [CVE-2026-28302](https://insights.sbomify.com/CVE-2026-28302/): SolarWinds Serv-U Insecure Direct Object Reference (IDOR) Vulnerability (critical 9.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-35211 and fix it if it is affected.

What it is: CVE-2021-35211 is a critical memory corruption vulnerability in Solarwinds Serv-U, published on 14 Jul 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: Yes. Attackers have exploited CVE-2021-35211 in the wild since at least 3 Nov 2021, including in ransomware campaigns.

Affected product: Solarwinds Serv-U. 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-2021-35211/ (Markdown: https://insights.sbomify.com/CVE-2021-35211/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-35211
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-35211
- OSV: https://osv.dev/vulnerability/CVE-2021-35211

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-35211/
Summaries are generated and may contain mistakes; the official description above is the record.