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CVE-2026-44332 medium CVSS 5.3

Vulnerability in github.com/gofiber/fiber/v3 (CVE-2026-44332)

Summary

Vulnerability in github.com/gofiber/fiber/v3 (CVE-2026-44332). Risk of unauthorized operations or information disclosure. Exploitable via Authorizer. Mitigation: upgrade to 3.3.0 or later.

Original description

The description as published by the source.

Summary

The default Authorizer function in GoFiber's BasicAuth middleware uses short-circuit evaluation that skips password hash comparison for non-existent usernames. With bcrypt-hashed passwords (the primary use case), the timing difference between a valid and invalid username is approximately 1,000,000:1 (~100ms vs ~100ns), enabling reliable remote username enumeration.

Vulnerable Code

File: middleware/basicauth/config.go, lines 126-138

if cfg.Authorizer == nil {
    verifiers := make(map[string]func(string) bool, len(cfg.Users))
    for u, hpw := range cfg.Users {
        v, err := parseHashedPassword(hpw)
        if err != nil {
            panic(err)
        }
        verifiers[u] = v
    }
    cfg.Authorizer = func(user, pass string, _ fiber.Ctx) bool {
        verify, ok := verifiers[user]
        return ok && verify(pass)   // line 137: short-circuit skips verify() if user unknown
    }
}

Data Flow

  1. Attacker sends Authorization: Basic
  2. BasicAuth middleware decodes credentials and calls cfg.Authorizer(user, pass, c)
  3. Map lookup verifiers[user] returns ok=false for non-existent users
  4. Go && short-circuit: false && verify(pass) returns immediately without calling verify()
  5. For valid users, verify(pass) executes bcrypt.CompareHashAndPassword() (line 167: ~100ms at default cost 10)
  6. Timing difference: ~100ns (invalid user) vs ~100ms (valid user) = 1,000,000:1 ratio

Timing comparison by hash type:

| Hash…

Source: GitHub Security Advisories (Global) NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-44332 has been found in github.com/gofiber/fiber/v3.
Attackers can target a specific entry point like Authorizer over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 5.3/10.
What to do: upgrade github.com/gofiber/fiber/v3 to 3.3.0 or later.
If unsure, ask your IT team or search "github.com/gofiber/fiber/v3 CVE-2026-44332" on the vendor's site.

CVE-2026-44332 (github.com/gofiber/fiber/v3) — CWE-203 / CVSS v3 5.3
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: Authorizer / subtle.ConstantTimeCompare
Patched: 3.3.0 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (CWE-203) exists in github.com/gofiber/fiber/v3. Attackers reach the vulnerable code path via Authorizer without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of github.com/gofiber/fiber/v3. Attack surface: Authorizer / subtle.ConstantTimeCompare.

🔥 Severity

Severity: Medium (CVSS 5.3/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 3.3.0.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'github.com/gofiber/fiber/v3' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    grep -r 'github.com/gofiber/fiber/v3' . | grep -v node_modules

    リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で github.com/gofiber/fiber/v3 を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Apply patch patch 
    Upgrade github.com/gofiber/fiber/v3 to 3.3.0

    ステージング環境で 3.3.0 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。

  3. 3
    Post-deployment verification verify 
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

go github.com/gofiber/fiber/v3
[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"3.3.0"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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