Vulnerability · CVE-2026-118651
Echo: Reverse Proxy Forwards Attacker-Supplied X-Real-IP to Upstream by Default
Published Oct 28, 2026 · catalog updated Oct 28, 2026 · Echo: Reverse Proxy Forwards
Last checked Nov 4, 2026. A connected source was read within the last 7 days.
Check if you run it
No confirmed exploitation is on record for CVE-2026-118651. EPSS is 0.21%. Act only if a listed version of Echo: Reverse Proxy Forwards is installed.
Gaps on this record
- The stored product name is a package slug. The name on this page is taken from the title (Echo: Reverse Proxy Forwards).
- No vendor fix or required action is stored. Compare the linked advisory before you change production.
- Severity
- Medium5.3
- Known exploitation
- Not in CISA/VulnCheck KEV
- EPSS
- 0.21%
- Remediation
- Advisory link
- Affected products
- Go github.com/labstack/echo/v4 · Go github.com/labstack/echo/v5 · golang github.com
## Summary The Echo proxy middleware ( ) preserves an incoming header verbatim and forwards it to the upstream service when is not configured — which is the default. Because any HTTP client can supply an arbitrary value, an attacker can cause Echo to relay a spoofed client IP address to every upstream service behind the proxy, undermining upstream IP-based access controls, rate limiting, audit logging, and geo-restriction. ## Affected Component - — , header-rewriting block (lines 351–355) ## Description ### The header-preservation condition passes spoofed values to upstream ( ) prepares forwarding headers before dispatching each request. The rewrite logic at lines 351-355 reads: The condition is (and therefore overwrites the header with a derived value) only when: - The header is absent — ; **or** - is explicitly configured — The condition is — and the header is left **unchanged** — when the request arrives with an header already set **and** is . Because leaves as , this is the out-of-the-box behaviour for every application that uses or without extra configuration. An attacker who sets to any value causes Echo to forward exactly that value to the upstream, with no modification or validation. ### The comment in the source code confirms intent and the security gap The inline comment at line 351-352 explicitly states: > "Basically it's not good practice to unconditionally pass incoming x-real-ip header to upstream. However, for backward compatibility, legacy behavior is preserved unless you configure Echo#IPExtractor." The framework is aware that the default is insecure and retains it for backward compatibility. No warning appears in the or documentation, so operators who follow the standard setup example receive a silently insecure proxy configuration. This is structurally identical to the documented insecurity in : > "Note: if you don't set explicitly, Echo fallback to legacy behavior, which is not a good choice." ### Full execution chain 1. Attacker sends to the Ech
Are you affected?
Enter the version you run. The result uses only the ranges stored on this record.
The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.
- Go github.com/labstack/echo/v44.0.0 → 4.16.2
- Go github.com/labstack/echo/v50 → 5.4.0
- golang github.comversion unspecified
How to fix CVE-2026-118651
Upgrade
CVE-2026-118651 lists a fix boundary at 4.16.2. Compare the installed build with that boundary before you change production.
Version check
Fixed in 5.4.0 · 1 other ranges on the advisory
Advisory
Open the cve_org record and follow its fix.
Official advisories
What to do
Three questions, each answered from this record only. Confirm the vendor advisory before you patch.
Should you patch?
No confirmed exploitation is on record for CVE-2026-118651. EPSS is 0.21%. Act only if a listed version of Echo: Reverse Proxy Forwards is installed.
Which versions are affected?
Compare what you have installed with 4.0.0 → 4.16.2, 0 → 5.4.0. Compare the installed version with the linked vendor advisory before you change production.
What should an analyst verify?
CWE-346. EPSS 0.21%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.
Code
The project this record applies to. Exploit listings stay in References.
Timeline
Detection, updates, and resolution for this record.
Oct 28, 2026 · GitLab Advisory Database
Detected
The Echo proxy middleware (middleware/proxy.go) preserves an incoming X-Real-IP header verbatim and forwards it to the upstream service when Echo#IPExtractor is not configured — which is the default. Because any HTTP client can supply an arbitrary X-Real-IP value, an attacker can cause Echo to relay a spoofed client IP address to every upstream service behind the proxy, undermining upstream IP-bas
Oct 28, 2026 · Go Vulnerability Database
Fix available
github.com/labstack/echo/v5 fixed in 5.4.0
Oct 28, 2026 · Go Vulnerability Database
Fix available
github.com/labstack/echo/v5 fixed in 5.4.0
Oct 28, 2026 · Go Vulnerability Database
Fix available
github.com/labstack/echo/v4 fixed in 4.16.2
Oct 28, 2026 · Go Vulnerability Database
Updated
## Summary The Echo proxy middleware ( ) preserves an incoming header verbatim and forwards it to the upstream service when is not configured — which is the default. Because any HTTP client can supply an arbitrary value, an attacker can cause Echo to relay a spoofed client IP address to every upstream service behind the proxy, undermining upstream IP-based access controls, rate limiting, audit log
Sources
- CVE.orgVulnerability recordCVE-2026-118651
Official CVE identifier
cve.org - FIRST EPSSExploitation probabilityCVE-2026-118651
30-day exploitation probability 0.21%
first.org - GitLab Advisory DatabasePackage advisoryCVE-2026-118651
The Echo proxy middleware (middleware/proxy.go) preserves an incoming X-Real-IP header verbatim and forwards it to the upstream service when Echo#IPExtractor is not configured — which is the default. Because any HTTP client can supply an arbitrary X-Real-IP value, an attacker can cause Echo to relay a spoofed client IP address to every upstream service behind the proxy, undermining upstream IP-bas
advisories.gitlab.com - Go Vulnerability DatabasePackage advisoryGHSA-99jh-6h7p-pp36
Echo: Reverse Proxy Forwards Attacker-Supplied X-Real-IP to Upstream by Default
osv.dev
References
Freshness
Last verified in this catalog Nov 4, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.
- FIRST EPSSNov 4, 2026
- GitLab Advisory DatabaseOct 30, 2026
- CVE.orgOct 29, 2026
- Go Vulnerability DatabaseOct 29, 2026