# CVE-2026-28313: SolarWinds Serv-U Insecure Direct Object Reference (IDOR) Vulnerability

> Attackers can exploit an IDOR flaw in SolarWinds Serv-U to hijack SMTP and take over arbitrary accounts.

- **Severity:** Critical 9.1 (`CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 21 Jul 2026
- **Updated:** 24 Jul 2026
- **Also known as:** GHSA-wpw8-5vq9-3rp5

## What is CVE-2026-28313?

CVE-2026-28313 is a critical missing authorization vulnerability in Solarwinds Serv-U, published on 21 Jul 2026. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

SolarWinds Serv-U is affected by an insecure direct object reference (IDOR) vulnerability that can lead to SMTP hijacking leading to arbitrary account takeover. The impact is lower in Windows deployments.

Weakness: CWE-639 (Authorization Bypass Through User-Controlled Key)

## Which versions are affected by CVE-2026-28313?

It affects 1 product.


Products: Solarwinds Serv-U.

## How do I fix CVE-2026-28313?

No fix has been published for CVE-2026-28313 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-28313 being exploited?

There is no known exploitation of CVE-2026-28313 in the wild and no public exploit code.

## 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-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)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-28313 and fix it if it is affected.

What it is: CVE-2026-28313 is a critical missing authorization vulnerability in Solarwinds Serv-U, published on 21 Jul 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-28313 in the wild and no public exploit code.

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-2026-28313/ (Markdown: https://insights.sbomify.com/CVE-2026-28313/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-28313
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-28313
- OSV: https://osv.dev/vulnerability/CVE-2026-28313

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-28313/
Summaries are generated and may contain mistakes; the official description above is the record.