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CVE-2026-107834 medium CVSS 5.3

Vulnerability in github.com/corazawaf/coraza/v3 (CVE-2026-107834)

Summary

Vulnerability in github.com/corazawaf/coraza/v3 (CVE-2026-107834). Risk of unauthorized operations or information disclosure. Exploitable via for. Mitigation: upgrade to 3.8.0 or later.

Original description

The description as published by the source.

Summary

defer temp.Close() sits inside a for loop in the multipart processor. Go defers run at function return, not loop end, so every file part in the request holds an open fd until ProcessRequest() exits. Send enough parts and you hit EMFILE. With CRS loaded, that flips MULTIPART_STRICT_ERROR to 1 and rule 200001 starts returning 400s, including on legitimate requests hitting the same condition.

Details

internal/bodyprocessors/multipart.go, line 69:

for {
    p, err := mr.NextPart()
    // ...
    temp, err := os.CreateTemp(storagePath, "crzmp*")
    defer temp.Close() // wrong scope
    io.Copy(temp, p)
}

Each iteration opens a temp file and defers its close. All of them stack up and fire together when ProcessRequest returns. 500 parts, 500 fds held simultaneously.

The body size limit (default 128MB) caps total bytes, not part count. A minimal file part (boundary line, Content-Disposition with filename=, one byte of content) is about 104 bytes. That's roughly 65,000 parts per 6.8MB of body, which on a standard Linux system (hard fd limit 65536) is enough to exhaust the table.

Fix is straightforward: call temp.Close() explicitly after io.Copy instead of deferring it.

PoC

Tested on v3.7.0 (db9850b), Go 1.25, Linux x86_64.

Add this file at internal/bodyprocessors/poc_fd_test.go and run:

go test -v -run TestMultipartFDLeak ./internal/bodyprocessors/...

package bodyprocessors_test

import (
	"fmt"
	"os…

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-2026-107834 has been found in github.com/corazawaf/coraza/v3.
Attackers can target a specific entry point like for 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/corazawaf/coraza/v3 to 3.8.0 or later.
If unsure, ask your IT team or search "github.com/corazawaf/coraza/v3 CVE-2026-107834" on the vendor's site.

CVE-2026-107834 (github.com/corazawaf/coraza/v3) — CWE-400 / CVSS v3 5.3
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: for / EMFILE / MULTIPART_STRICT_ERROR / ProcessRequest
Patched: 3.8.0 — 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-400) exists in github.com/corazawaf/coraza/v3. Attackers reach the vulnerable code path via for without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of github.com/corazawaf/coraza/v3. Attack surface: for / EMFILE / MULTIPART_STRICT_ERROR / ProcessRequest.

🔥 Severity

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

🔧 How to fix

Update to 3.8.0.

🛡️ 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/corazawaf/coraza/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/corazawaf/coraza/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/corazawaf/coraza/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/corazawaf/coraza/v3 to 3.8.0

    ステージング環境で 3.8.0 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/corazawaf/coraza/v3
[{"type":"SEMVER","events":[{"introduced":"3.0.0"},{"fixed":"3.8.0"}]}]

References

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