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.
CVE-2026-45045
MEDIUMPre-NVD 5.35.3—
EchelonGraph scoreMEDIUM confidence
This medium-severity CVE scores 5.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.5%, top 63% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
Triggered by: NVD CVSS baseline
Sources: epss, secondary
5.3
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
- Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 5.3Exploit: NoneExposed: 0
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 5.3
- EG Score
- 5.3(medium)
- EG Risk
- —
- EPSS
- 37.5%
- KEV
- Not listed
Published
July 2, 2026
Last Modified
July 15, 2026
Advisory Details (7)
Auto-updated Jul 8, 2026Patch available. Sources: github_release, github, github_commit, github_pr.
github Patch Available
X-Real-IP Spoofing via Header.Add() in BalancerForward · Advisory · gofiber/fiber · GitHub
https://github.com/gofiber/fiber/security/advisories/GHSA-gcfq-8gqf-4876github_release Patch Available
v3.3.0
Patch available: gofiber/fiber v3.3.0
https://github.com/gofiber/fiber/releases/tag/v3.3.0github_release Patch Available
v2.52.14
Patch available: gofiber/fiber v2.52.14
https://github.com/gofiber/fiber/releases/tag/v2.52.14github_pr Patch Available
🐛 fix(proxy): backport BalancerForward X-Real-IP overwrite fix to v2
Patch available: gofiber/fiber v2.52.14 (PR #4495 merged 2026-07-03)
https://github.com/gofiber/fiber/pull/4495github_pr Patch Available
🐛 fix(proxy): Ensure BalancerForward overwrites X-Real-IP header
Patch available: gofiber/fiber v3.3.0 (PR #4260 merged 2026-05-08)
https://github.com/gofiber/fiber/pull/4260github_commit Patch Available
commit 33c9501288ab (gofiber/fiber)
Patch available: gofiber/fiber v2.52.14 (contains commit 33c9501288ab)
https://github.com/gofiber/fiber/commit/33c9501288ab47a429c8b5e701493f0c3c0af37dgithub_commit Patch Available
commit 1403cc8292da (gofiber/fiber)
Patch available: gofiber/fiber v3.3.0 (contains commit 1403cc8292da)
https://github.com/gofiber/fiber/commit/1403cc8292da3220e9316960b4030cc722a0f396Vendor Advisories for CVE-2026-45045(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Affected Packages
(2 across 1 ecosystem)
Go(2)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| github.com/gofiber/fiber/v2 | — | — | — |
| github.com/gofiber/fiber/v3 | — | 3.3.0 | — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 7× in last 7d / 15× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-07-22 14:08 UTCEPSS rescore
- 2026-07-21 15:24 UTCEPSS rescore
- 2026-07-20 17:08 UTCEPSS rescore
- 2026-07-19 14:31 UTCEPSS rescore
- 2026-07-19 02:29 UTCEPSS rescore
- 2026-07-18 10:04 UTCEPSS rescore
- 2026-07-16 17:03 UTCEPSS rescore
- 2026-07-15 16:57 UTCEPSS rescore
- 2026-07-15 02:00 UTCEPSS rescore
- 2026-07-13 22:30 UTCEPSS rescore
- 2026-07-13 06:13 UTCEPSS rescore
- 2026-07-12 05:46 UTCEPSS rescore
- 2026-07-11 08:27 UTCEPSS rescore
- 2026-07-09 19:10 UTCEPSS rescore
- 2026-07-02 14:01 UTCEG score recompute
Related CVEs(same CWE)
Same CWE
10 shownCWE-290
Frequently asked(5)
What is CVE-2026-45045?
CVE-2026-45045 is a medium vulnerability published on July 2, 2026. 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…
When was CVE-2026-45045 disclosed?
CVE-2026-45045 was first published in the National Vulnerability Database on July 2, 2026, with the most recent update on July 15, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-45045 actively exploited?
CVE-2026-45045 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 37.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-45045?
CVE-2026-45045 has a CVSS v3 base score of 5.3 (NVD).
How do I remediate CVE-2026-45045?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-45045, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-45045
Is Your Infrastructure Affected by CVE-2026-45045?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.