CVE-2026-45045

mediumCVSS 5.3covered by 1 sourcefirst seen 2026-07-08

Fiber is an Express inspired web framework written in Go. Prior to 3.3.0 and 2.52.14, the BalancerForward proxy helper in middleware/proxy/proxy.go uses Header.Add() instead of Header.Set() when injecting X-Real-IP, allowing an attacker-supplied first X-Real-IP value to be forwarded to upstream servers for logging, rate limiting, and access control. This issue is fixed in version 3.3.0 and 2.52.14.

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Exploitation outlook

Low exploitation risk0.46% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 37% of all EPSS-scored CVEs.

Advisory coverage (1)

mediumCVE-2026-45045: Fiber is an Express inspired web framework written in Go. Prior to 3.3.0 and 2.52.14, the Bala…nvd · 2026-07-08

External references

NVD record for CVE-2026-45045

CVE.org record

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