vulnerability / NVI-00010138 / Revision 3
chi: Client IP spoofing in ClientIPFromXFF via X-Forwarded-For
GitHub lists this reviewed advisory for github.com/go-chi/chi/v5. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
4.8 medium
GitHub source severity; exploitability and local consequence require separate evidence.
As of · GitHub Advisory Database
0.129%
FIRST EPSS model v2026.06.15; exploitation probability over 30 days, percentile 0.026. Missing scores are unknown.
As of · FIRST EPSS
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
github.com/go-chi/chi/v5
source listed<= 5.3.2
### Summary `ClientIPFromXFF` skips any `X-Forwarded-For` entry in a configured trusted CIDR but never verifies that the direct TCP peer in `http.Request.RemoteAddr` belongs to that CIDR. A client that can reach the Go server directly can therefore append a trusted-looking proxy address and choose the client IP returned by `middleware.GetClientIP`. The attack is remote and requires one unauthenticated HTTP request with no user interaction (AV:N/AC:L/PR:N/UI:N). It changes security decisions and exposes one protected handler within the same application (S:U/C:L/I:L); no availability loss was observed (A:N). **Preconditions:** The application uses `ClientIPFromXFF` and makes the origin server reachable by an anonymous client outside the configured trusted-proxy CIDRs. No victim interaction is required. 1. Send `GET /admin` directly to the origin with no `X-Forwarded-For` header. 2. Observe a `403 Forbidden` response and an empty derived client IP. 3. Repeat the request with `X-Forwarded-For: 10.0.0.7, 198.51.100.42`. 4. Observe `200 OK` and `client-ip="10.0.0.7"`. Expected: the untrusted direct peer prevents the forwarding chain from being accepted. ### Details The vulnerable c
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. FIRST EPSS
A fixed release is not deployment evidence.
Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.
04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
05 / Provenance
Sources you can inspect
Each assertion retains its source. Mirrored records may repeat one underlying publisher; additional links are not independent corroboration.
- GHSA-j6qf-3m9c-vwj3 ↗
GitHub Advisory Database · vendor advisory
Observed . GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.
- CVE-2026-114437 ↗
FIRST EPSS · official catalog
Observed . FIRST EPSS; probability of exploitation in the next 30 days, not local compromise. Dataset date/model retained; FIRST services terms apply.
Public revision history
Only published revisions appear here. Routine fetches do not create a material-change event.
- Revision 3 ·
Dated EPSS estimate updated; this is not a new disclosure or proof of exploitation.
- Revision 2 ·
Dated EPSS estimate updated; this is not a new disclosure or proof of exploitation.
- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.