vulnerability / NVI-00008970 / Revision 2
Echo has Rate Limiter Bypass via Spoofed X-Forwarded-For Header in Default Configuration
GitHub lists this reviewed advisory for github.com/labstack/echo/v5, github.com/labstack/echo/v4. 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.
5.3 medium
GitHub source severity; exploitability and local consequence require separate evidence.
As of · GitHub Advisory Database
0.415%
FIRST EPSS model v2026.06.15; exploitation probability over 30 days, percentile 0.35846. 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/labstack/echo/v5
source listed< 5.1.0
## Summary When `echo.New()` is used without explicitly setting `Echo#IPExtractor`, the `RealIP()` method falls back to reading the client-supplied `X-Forwarded-For` (or `X-Real-IP`) header without any proxy-origin validation. The default `RateLimiter()` middleware derives its per-client identifier from `ctx.RealIP()`, so an attacker can rotate arbitrary values in the `X-Forwarded-For` header on each request to obtain a fresh rate-limit bucket and bypass IP-based throttling entirely. ## Affected Component - `context.go` — `(*Context).RealIP()` (lines 186–208), legacy fallback branch (lines 190–200) - `middleware/rate_limiter.go` — `DefaultRateLimiterConfig.IdentifierExtractor` (lines 46–58); `RateLimiter()` (lines 71–76) - `echo.go` — `New()` (lines 326–343), `IPExtractor` left `nil` by default ## Description ### `RealIP()` unconditionally trusts `X-Forwarded-For` when `IPExtractor` is unset `Context.RealIP()` (`context.go:186-208`) first checks `c.echo.IPExtractor`. When this field is `nil` (the default for `echo.New()`), it falls through to legacy behavior and returns the **first IP** from the `X-Forwarded-For` header — the position an attacker has full control over: ```go
github.com/labstack/echo/v4
source listed>= 4.0.0, <= 4.16.2
## Summary When `echo.New()` is used without explicitly setting `Echo#IPExtractor`, the `RealIP()` method falls back to reading the client-supplied `X-Forwarded-For` (or `X-Real-IP`) header without any proxy-origin validation. The default `RateLimiter()` middleware derives its per-client identifier from `ctx.RealIP()`, so an attacker can rotate arbitrary values in the `X-Forwarded-For` header on each request to obtain a fresh rate-limit bucket and bypass IP-based throttling entirely. ## Affected Component - `context.go` — `(*Context).RealIP()` (lines 186–208), legacy fallback branch (lines 190–200) - `middleware/rate_limiter.go` — `DefaultRateLimiterConfig.IdentifierExtractor` (lines 46–58); `RateLimiter()` (lines 71–76) - `echo.go` — `New()` (lines 326–343), `IPExtractor` left `nil` by default ## Description ### `RealIP()` unconditionally trusts `X-Forwarded-For` when `IPExtractor` is unset `Context.RealIP()` (`context.go:186-208`) first checks `c.echo.IPExtractor`. When this field is `nil` (the default for `echo.New()`), it falls through to legacy behavior and returns the **first IP** from the `X-Forwarded-For` header — the position an attacker has full control over: ```go
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-246p-cpwv-v3jq ↗
GitHub Advisory Database · vendor advisory
Observed . GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.
- CVE-2026-118653 ↗
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 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.