Summary
Echo: X-Real-IP extractor trusts the header value instead of the sending peer
Affected versions and patch
All v5 releases from v5.0.0 through v5.4.0 are affected. Upgrade to v5.4.1.
The patch validates the direct peer before accepting a syntactically valid X-Real-IP value, restoring the v4 trust model. Fix commit.
Workarounds
Use ExtractIPDirect until upgrading, or ensure that only trusted proxies can reach Echo and that they replace client-supplied forwarding headers. Configure trusted proxy ranges narrowly for the deployment.
Credits
Reported and patched by @rm-Umar. @Duodum independently reported the same issue in GHSA-c3r7-8j36-7mx8, which is tracked as a duplicate of this advisory.
Impact
In Echo v5, ExtractIPFromRealIPHeader checked whether the address supplied in X-Real-IP belonged to a trusted range instead of checking the address of the direct network peer. An untrusted client could therefore supply a loopback or private address and have it returned by c.RealIP() with the extractor's default trust options.
Applications using this extractor for IP allowlists, IP-based rate limiting, audit logs or forwarding headers could accept a spoofed client identity. Exploitation requires that the attacker can reach Echo directly or that an intervening proxy passes through the attacker's X-Real-IP value. Applications using the default direct IP extractor are unaffected. Echo v4 is unaffected by this v5 regression.
CVE-2026-118265 has a CVSS score of 5.3 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (5.4.1); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2026-118265? CVE-2026-118265 is a medium-severity security vulnerability in github.com/labstack/echo/v5 (go), affecting versions >= 5.0.0, < 5.4.1. It is fixed in 5.4.1.
- How severe is CVE-2026-118265? CVE-2026-118265 has a CVSS score of 5.3 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of github.com/labstack/echo/v5 are affected by CVE-2026-118265? github.com/labstack/echo/v5 (go) versions >= 5.0.0, < 5.4.1 is affected.
- Is there a fix for CVE-2026-118265? Yes. CVE-2026-118265 is fixed in 5.4.1. Upgrade to this version or later.
- Is CVE-2026-118265 exploitable, and should I be worried? Whether CVE-2026-118265 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-118265 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-118265? Upgrade
github.com/labstack/echo/v5to 5.4.1 or later.