# CVE-2021-35247: SolarWinds Serv-U Improper Input Validation

> Insufficient input validation in Serv-U's LDAP login allowed unsanitized characters, though no downstream impact was detected.

- **Severity:** Medium 4.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N`)
- **Exploited in the wild:** Yes, since 21 Jan 2022 (CISA KEV)
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 7 Jan 2022
- **Updated:** 21 Oct 2025
- **Also known as:** GHSA-jqwj-9jvg-583v

## What is CVE-2021-35247?

CVE-2021-35247 is a medium-severity vulnerability in Solarwinds Serv-U, published on 7 Jan 2022. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

Serv-U web login screen to LDAP authentication was allowing characters that were not sufficiently sanitized. SolarWinds has updated the input mechanism to perform additional validation and sanitization. Please Note: No downstream affect has been detected as the LDAP servers ignored improper characters. To insure proper input validation is completed in all environments. SolarWinds recommends scheduling an update to the latest version of Serv-U.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2021-35247?

It affects 1 product.


Products: Solarwinds Serv-U.

## How do I fix CVE-2021-35247?

No fix has been published for CVE-2021-35247 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 4 Feb 2022.

## Is CVE-2021-35247 being exploited?

Yes. Attackers have exploited CVE-2021-35247 in the wild since at least 21 Jan 2022.

## Other vulnerabilities in Solarwinds Serv-U

- [CVE-2021-35211](https://insights.sbomify.com/CVE-2021-35211/): SolarWinds Serv-U Remote Code Execution (critical 9.0, exploited in the wild)
- [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-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-2021-35247 and fix it if it is affected.

What it is: CVE-2021-35247 is a medium-severity vulnerability in Solarwinds Serv-U, published on 7 Jan 2022. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: Yes. Attackers have exploited CVE-2021-35247 in the wild since at least 21 Jan 2022.

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-2021-35247/ (Markdown: https://insights.sbomify.com/CVE-2021-35247/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-35247
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-35247
- OSV: https://osv.dev/vulnerability/CVE-2021-35247

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-35247/
Summaries are generated and may contain mistakes; the official description above is the record.