CVE-2026-118265 is a medium-severity (CVSS 5.3) CWE-348 vulnerability in github.com/labstack/echo/v5. A fix is available for github.com/labstack/echo/v5 — see the affected versions and patch details below.
Echo: X-Real-IP extractor trusts the header value instead of the sending peer
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-118265.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-118265 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 397,508 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
github.com/labstack/echo/v5Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
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.
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/labstack/echo/v5 | ≥ 5.0.0&&< 5.4.1 | 5.4.1go get github.com/labstack/echo/v5@v5.4.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/labstack/echo/v5, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/labstack/echo/v5 to 5.4.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-118265 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Frequently Asked Questions
Is CVE-2026-118265 in your dependencies?
Find it across Go, including transitive dependencies.