# CVE-2026-21862: RustFS sourceIp bypass via spoofed X-Forwarded-For/Real-IP headers

> Attackers can bypass IP-based access controls in RustFS by spoofing X-Forwarded-For headers, allowing unauthorized access to resources.

- **Severity:** High 7.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 3 Feb 2026
- **Updated:** 3 Feb 2026
- **Also known as:** GHSA-fc6g-2gcp-2qrq

## What is CVE-2026-21862?

CVE-2026-21862 is a high-severity authentication bypass vulnerability in rustfs, published on 3 Feb 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

RustFS is a distributed object storage system built in Rust. Prior to version alpha.78, IP-based access control can be bypassed: get_condition_values trusts client-supplied X-Forwarded-For/X-Real-Ip without verifying a trusted proxy, so any reachable client can spoof aws:SourceIp and satisfy IP-allowlist policies. This issue has been patched in version alpha.78.

Weakness: CWE-290 (Authentication Bypass by Spoofing)

## Which versions are affected by CVE-2026-21862?

2 open source packages ship an affected version, including rustfs. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `rustfs` | crates.io | All versions | 1.0.0-alpha.78 |
| `rustfs` | crates.io | All versions | 1.0.0-alpha.78 |

Products: Rustfs Rustfs.

## How do I fix CVE-2026-21862?

Upgrade rustfs to 1.0.0-alpha.78 or later.

## Is CVE-2026-21862 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-21862 exists.

## Other vulnerabilities in rustfs

- [CVE-2025-68926](https://insights.sbomify.com/CVE-2025-68926/): RustFS has a gRPC Hardcoded Token Authentication Bypass (critical 9.8)
- [CVE-2026-27822](https://insights.sbomify.com/CVE-2026-27822/): Rust has Critical Stored XSS in Preview Modal, leading to Administrative Account Takeover (critical 9.1)
- [CVE-2025-68705](https://insights.sbomify.com/CVE-2025-68705/): RustFS Path Traversal Vulnerability (high 8.8)
- [CVE-2026-40937](https://insights.sbomify.com/CVE-2026-40937/): RustFS: Missing admin authorization on notification target endpoints allows unauthenticated configuration of event webhooks (high 8.3)
- [CVE-2026-27607](https://insights.sbomify.com/CVE-2026-27607/): RustFS's Missing Post Policy Validation leads to Arbitrary Object Write (high 8.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-21862 and fix it if it is affected.

What it is: CVE-2026-21862 is a high-severity authentication bypass vulnerability in rustfs, published on 3 Feb 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-21862 exists.

Affected packages and fixed versions:
- rustfs (crates.io): affected all versions; fixed in 1.0.0-alpha.78
- rustfs (crates.io): affected all versions; fixed in 1.0.0-alpha.78

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-2026-21862/ (Markdown: https://insights.sbomify.com/CVE-2026-21862/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-21862
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-21862
- OSV: https://osv.dev/vulnerability/CVE-2026-21862

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-21862/
Summaries are generated and may contain mistakes; the official description above is the record.