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CVE-2026-104774 medium CVSS 5.8

Vulnerability in github.com/corazawaf/coraza/v3 (CVE-2026-104774)

Summary

Vulnerability in github.com/corazawaf/coraza/v3 (CVE-2026-104774). Risk of unauthorized operations or information disclosure. Exploitable via strconv.ParseInt. Mitigation: upgrade to 3.8.0 or later.

Original description

The description as published by the source.

Summary

The t:jsDecode transformation in Coraza WAF contains an off-by-one error when parsing octal escape sequences. A backslash character was incorrectly included in the octal number buffer, causing strconv.ParseInt to fail for every octal escape sequence and return a null byte instead of the decoded value that would normally be returned. This will cause all JS-escaped payloads to be corrupted, thus leading to the bypassing of these WAF rules when WAF rules that rely on jsDecode for normalization are enabled.

Therefore, a real-world attack scenario: an attacker could use JavaScript octal escape sequences (\ooo) to encode attack syntax. Although the WAF cannot decode these sequences correctly, the target backend (such as a browser or application) can parse them as expected.

Details

Vulnerable code: internal/transformations/js_decode.go:64-70.

case (i+1 < inputLen) && isodigit(input[i+1]):
    /* \OOO (only one byte, \000 - \377) */
    buf := make([]byte, 3)
    j := 0

    for (i+1+j < inputLen) && (j < 3) {
        buf[j] = input[i+j]     // this should be `input[i+1+j]`
        j++
        if !isodigit(input[i+j]) {
            break
        }
    }

This is because, when entering octal mode, the loop variable i points to the backslash character \. Before entering octal mode, the pointer does not cross the backslash (unlike in the \u and \x cases, where i+N is used as the index). Line 65 uses input[i+j], so when j=0, the back…

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-2026-104774 has been found in github.com/corazawaf/coraza/v3.
Attackers can target a specific entry point like strconv.ParseInt over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 5.8/10.
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-2026-104774" on the vendor's site.

CVE-2026-104774 (github.com/corazawaf/coraza/v3) — CWE-172 / CVSS v3 5.8
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: strconv.ParseInt / jsDecode / SecRuleEngine / SecRequestBodyAccess
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-172) exists in github.com/corazawaf/coraza/v3. Attackers reach the vulnerable code path via strconv.ParseInt without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of github.com/corazawaf/coraza/v3. Attack surface: strconv.ParseInt / jsDecode / SecRuleEngine / SecRequestBodyAccess.

🔥 Severity

Severity: Medium (CVSS 5.8/10). 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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