RustFS has SourceIp bypass via spoofed X-Forwarded-For/Real-IP headers

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

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 · score source

EPSS

• CVE-2026-21862: 0.25% estimated exploitation activity in the next 30 days; percentile 16.59 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary IP-based access control can be bypassed: getconditionvalues 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. Details - Vulnerable code: rustfs/src/auth.rs:289-304 sets remoteaddr from X-Forwarded-For/X-Real-Ip, then inserts SourceIp via getsourceipraw, with no trust boundary or proxy validation: - let remoteaddr = header.get("x-forwarded-for").andthen(...).orelse(|| header.get("x-real-ip")...).unwrapor("127.0.0.1"); - args.insert("SourceIp", vec![getsourceipraw(header, remoteaddr)]); - This value feeds IAM/bucket policy evaluation in rustfs/src/storage/access.rs (authorization path), so any request that forges the header can meet aws:SourceIp conditions. - No authentication is required beyond the request itself; the header is taken at face value even on direct connections. PoC rustfs-auth-trusted-ip-header-spoofing-poc.tar.gz Steps (already included in…

Published by the source

3 Feb 2026, 17:31 UTC

Last modified by the source

3 Feb 2026, 18:55 UTC

Source last checked

26 Oct 2026, 15:39 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-fc6g-2gcp-2qrq

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# Patch Next advisory brief: CVE-2026-21862

Advisory: RustFS has SourceIp bypass via spoofed X-Forwarded-For/Real-IP headers
IDs: CVE-2026-21862, GHSA-fc6g-2gcp-2qrq
Record: https://patchnext.com/advisories/cve-2026-21862 (revision 1, source checked 26 Oct 2026, 15:39 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: rustfs 1.0.0-alpha.78. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io rustfs: affected < 1.0.0-alpha.78; fixed in 1.0.0-alpha.78

## Suggested inspection (read-only)
- crates.io rustfs: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on rustfs.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-fc6g-2gcp-2qrq (GitHub-reviewed advisory GHSA-fc6g-2gcp-2qrq lists affected ranges: crates.io rustfs >=0 <1.0.0-alpha.78)

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