CVE-2026-45045: Fiber is an Express inspired web framework written in Go

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MEDIUM 5.3REMOTEUPGRADE

CVE-2026-45045 is a medium-severity flaw (CVSS 5.3) affecting fiber. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	5.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 60%)
CISA exploited list	No
Weakness	CWE-290
Published	2026-07-08
Last modified	2026-10-25

Publisher (CNA): GitHub, Inc. · Vendor: gofiber

Last updated 2026-10-25 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-07-08 20:16 UTCPublished CVE record published
2026-10-25 17:10 UTCUpdated Record last modified

gofiber fiber UPGRADE

Affected: < 2.52.14 · >= 3.0.0 and < 3.3.0

Fixed in: 2.52.14, 3.3.0

Safe to downgrade to: a release before 3.0.0

1. Check installed version

apt-cache policy fiber || rpm -q fiber || fiber --version

2. UPGRADE to 2.52.14 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade fiber

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade fiber

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 3.0.0 (Debian / Ubuntu)

apt-cache madison fiber sudo apt install fiber=<VERSION_BEFORE_3.0.0> sudo apt-mark hold fiber

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list fiber sudo dnf downgrade fiber-<VERSION_BEFORE_3.0.0> sudo dnf versionlock add fiber

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-45045?

fiber: upgrade to 2.52.14, 3.3.0. Exact commands for each OS are on this page.

Is CVE-2026-45045 being exploited?

CVE-2026-45045 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-45045 affect?

CVE-2026-45045 affects fiber. Severity is medium (CVSS 5.3). 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-sup

How urgent is CVE-2026-45045?

Priority 39/100. Public exploit reference; Remotely exploitable, no login, no user action

Related CVEs

CVE-2026-44332 MEDIUM 5.3 UPGRADE Fiber is an Express inspired web framework written in Go
CVE-2026-53624 MEDIUM 4.8 UPGRADE Fiber is an Express inspired web framework written in Go

References

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