GHSA-X26Q-WVHG-FH4M

Vulnerability from github – Published: 2026-10-08 17:46 – Updated: 2026-10-09 17:32
VLAI
Summary
Coraza: ProcessURI silently drops QUERY_STRING and ARGS_GET on URI parse failure — defense-in-depth bypass for non-net/http integrations
Details

Root Cause

File: internal/corazawaf/transaction.go, lines 834–866.

parsedURL, err := url.ParseRequestURI(uri)
query := ""
if err != nil {
    tx.variables.urlencodedError.Set(err.Error())
    path = uri
    tx.variables.requestURI.Set(uri)
    /*
        tx.Variables.VARIABLE_URI_PARSE_ERROR.Set("1")
        posRawQuery := strings.Index(uri, "?")
        if posRawQuery != -1 {
            tx.ExtractArguments("GET", uri[posRawQuery+1:])
            path = uri[:posRawQuery]
            query = uri[posRawQuery+1:]
        } else {
            path = uri
        }
        tx.Variables.RequestUri.Set(uri)
    */
} else {
    tx.ExtractGetArguments(parsedURL.RawQuery)   // only path that populates ARGS_GET
    tx.variables.requestURI.Set(parsedURL.String())
    path = parsedURL.Path
    query = parsedURL.RawQuery
}
...
tx.variables.queryString.Set(query)

When url.ParseRequestURI(uri) returns an error — which Go's stdlib does for any URI containing raw control bytes (\x00, \n, \r, \t, other 0x00–0x1F, 0x7F) — the error branch silently produces an empty QUERY_STRING and an empty ARGS_GET collection. The fallback logic that should split on ? and populate the GET arguments from the raw tail is already present in the source as a commented-out block, referencing a VARIABLE_URI_PARSE_ERROR variable that was never wired up.

Consequences on the error branch:

  • ARGS_GET / ARGS_GET_NAMES / ARGS (union) are empty — ExtractGetArguments is never called.
  • QUERY_STRING is empty (initial query := "" at line 835 persists through to queryString.Set(query) at line 866).
  • REQUEST_FILENAME / REQUEST_BASENAME contain the entire URI including any ?… query suffix (because path = uri at line 838 bypasses the parse, and the subsequent strings.LastIndexAny(path, "/\\") runs over the raw URI).
  • URLENCODED_ERROR is set to the Go error message. That variable is also set by the urlencoded body processor on body-decode failures, so an operator cannot distinguish "malformed URI" from "malformed request body" without string-matching the error text.
  • REQUEST_URI_RAW (set unconditionally at line 822, before the parse) is populated correctly.

Any rule targeting ARGS_GET, ARGS, ARGS_NAMES, ARGS_GET_NAMES, or QUERY_STRING — which is the default target set for the vast majority of OWASP CRS GET-side signature rules — does not fire against attacker content that reaches Coraza via a URI Go's net/url rejects.

Reachability

This issue does not affect the standard coraza/v3/http + net/http integration. Go's http.ReadRequest calls url.ParseRequestURI first and rejects malformed URIs with 400 Bad Request before ProcessURI is invoked. Verified experimentally against a Coraza-wrapped net/http server — a raw request with a control-byte-laced URI produced HTTP 400, and the handler was never reached.

The bug is reachable when an integration forwards raw URI bytes to tx.ProcessURI directly, bypassing Go's HTTP parser:

  • coraza-spoa — HAProxy SPOP agent. Receives URI from HAProxy, which permits bytes net/http rejects.
  • coraza-proxy-wasm — Envoy WASM filter. Passes the :path pseudo-header from Envoy.
  • Custom FFI/WASM hosts and any embedder calling tx.ProcessURI(rawURI, method, httpVersion) with bytes not pre-validated by Go's URL parser.

This gates the attack to Attack Complexity:High — a standard Go HTTP deployment is not exposed.

Proof of Concept

Direct-API reproduction (simulating the non-net/http integration path):

waf, _ := coraza.NewWAF(coraza.NewWAFConfig().WithDirectives(`
SecRuleEngine On
SecRule ARGS_GET     "@contains ATTACK_HERE_XYZ" "id:9001,phase:1,deny,status:403"
SecRule QUERY_STRING "@contains ATTACK_HERE_XYZ" "id:9002,phase:1,deny,status:403"
`))

for _, uri := range []string{
    "/search?q=ATTACK_HERE_XYZ",                    // baseline
    "/search?q=ATTACK_HERE_XYZ\x00&y=1",            // NUL byte
    "/search?q=ATTACK_HERE_XYZ\ninjected: header",  // bare LF
    "/search?q=ATTACK_HERE_XYZ\rhdr: x",            // bare CR
    "/search?q=ATTACK_HERE_XYZ\tx=1",               // tab
} {
    tx := waf.NewTransaction()
    tx.ProcessURI(uri, "GET", "HTTP/1.1")
    it := tx.ProcessRequestHeaders()
    // inspect tx.Variables().QueryString().Get() and tx.Variables().ArgsGet().FindAll()
    tx.Close()
}

Observed:

URI QUERY_STRING ARGS_GET interrupted?
/search?q=ATTACK_HERE_XYZ q=ATTACK_HERE_XYZ 1 entry yes (403)
/search?q=ATTACK_HERE_XYZ\x00&y=1 "" 0 entries no — BYPASS
/search?q=ATTACK_HERE_XYZ\ninjected: header "" 0 entries no — BYPASS
/search?q=ATTACK_HERE_XYZ\rhdr: x "" 0 entries no — BYPASS
/search?q=ATTACK_HERE_XYZ\tx=1 "" 0 entries no — BYPASS

REQUEST_URI_RAW is populated correctly in every case (line 822 sets it before the parse), so a rule written against REQUEST_URI_RAW still catches the attack. CRS and most operator-written rules target ARGS_GET / ARGS / QUERY_STRING — those do not fire.

HTTP-layer reachability check (stock net/http):

$ printf 'GET /?q=ATTACK_HERE_XYZ\x00&y=1 HTTP/1.1\r\nHost: x\r\n\r\n' | nc 127.0.0.1 8092
HTTP/1.1 400 Bad Request

Confirms the exposure is limited to non-net/http integrations.

Mitigation

Recommended fixes, in order:

1. Re-enable the existing fallback and wire up URI_PARSE_ERROR

The code to fix this is already present as a commented-out block at transaction.go:840–851. Re-enable it, promote the referenced VARIABLE_URI_PARSE_ERROR to a real transaction variable, and populate ARGS_GET / QUERY_STRING from the raw ?… tail:

if err != nil {
    tx.variables.urlencodedError.Set(err.Error())
    tx.variables.uriParseError.Set("1")               // new variable
    tx.variables.requestURI.Set(uri)
    if i := strings.Index(uri, "?"); i != -1 {
        path = uri[:i]
        query = uri[i+1:]
        tx.ExtractGetArguments(query)                  // populate ARGS_GET
    } else {
        path = uri
    }
} else {
    ...
}

2. Ship a companion rule in coraza.conf-recommended

SecRule URI_PARSE_ERROR "@eq 1" \
    "id:'200010',phase:1,t:none,log,deny,status:400,msg:'URI failed to parse'"

This gives operators a fail-closed default (analogous to rule 200003 for multipart strict error and rule 200002 for body-parse error), so non-net/http integrations at least stop the request regardless of downstream rule coverage.

3. Do not overload URLENCODED_ERROR

The current code uses URLENCODED_ERROR for URI parse failures. That variable is also set by the urlencoded body processor on body-decode errors; operators cannot distinguish the two causes without string-matching the error text, and any rule they add will fire on both classes of failure. A dedicated URI_PARSE_ERROR variable (per the commented-out TODO) is the right shape.

Affected versions

All releases on the v3 branch (>= 3.0.0, <= 3.7.0); the silent-drop behavior has been present since the first v3 release. Only deployments using non-net/http integrations (coraza-spoa, coraza-proxy-wasm, custom FFI) are exposed in practice.

References

  • internal/corazawaf/transaction.go lines 834–866 (ProcessURI error branch)
  • internal/corazawaf/transaction.go line 822 (REQUEST_URI_RAW is populated before the parse, which is why REQUEST_URI_RAW-targeted rules still catch the attack)
  • Commented-out fallback at lines 840–851 referencing VARIABLE_URI_PARSE_ERROR
  • CWE-20 — Improper Input Validation
  • CWE-436 — Interpretation Conflict

Severity (revised 2026-10-02)

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N (4.0, Medium).

Attack Complexity stays High: the bypass only applies to integrations that pass Coraza a raw URI that Go's URL parser rejects, which net/http does not. The previous vector scored Integrity High (6.8); it is scored here like Coraza's other inspection bypasses.

Impact metrics follow the convention used across Coraza's WAF-bypass advisories: the vulnerable component is Coraza, but the impact lands on the protected application, so Scope is Changed. The bypass hides a payload from inspection; the application still has to be vulnerable to it, so Integrity is Low and Confidentiality is not scored separately.

AI involvement in this section: Claude Opus 5.5 (Anthropic), via Claude Code, re-derived the CVSS vector from the project's triage guidance (AGENTS.md, "CVSS preconditions get verified, not copied from the report") and drafted this text. A human maintainer (fzipi) chose the S:C/I:L impact convention and directed this update.

Show details on source website

{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/corazawaf/coraza/v3"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.0.0"
            },
            {
              "fixed": "3.8.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-107825"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-20",
      "CWE-436"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-10-08T17:46:00Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "## Root Cause\n\nFile: `internal/corazawaf/transaction.go`, lines 834\u2013866.\n\n```go\nparsedURL, err := url.ParseRequestURI(uri)\nquery := \"\"\nif err != nil {\n    tx.variables.urlencodedError.Set(err.Error())\n    path = uri\n    tx.variables.requestURI.Set(uri)\n    /*\n        tx.Variables.VARIABLE_URI_PARSE_ERROR.Set(\"1\")\n        posRawQuery := strings.Index(uri, \"?\")\n        if posRawQuery != -1 {\n            tx.ExtractArguments(\"GET\", uri[posRawQuery+1:])\n            path = uri[:posRawQuery]\n            query = uri[posRawQuery+1:]\n        } else {\n            path = uri\n        }\n        tx.Variables.RequestUri.Set(uri)\n    */\n} else {\n    tx.ExtractGetArguments(parsedURL.RawQuery)   // only path that populates ARGS_GET\n    tx.variables.requestURI.Set(parsedURL.String())\n    path = parsedURL.Path\n    query = parsedURL.RawQuery\n}\n...\ntx.variables.queryString.Set(query)\n```\n\nWhen `url.ParseRequestURI(uri)` returns an error \u2014 which Go\u0027s stdlib does for any URI containing raw control bytes (`\\x00`, `\\n`, `\\r`, `\\t`, other `0x00\u20130x1F`, `0x7F`) \u2014 the error branch silently produces an empty `QUERY_STRING` and an empty `ARGS_GET` collection. The fallback logic that should split on `?` and populate the GET arguments from the raw tail is already present in the source as a commented-out block, referencing a `VARIABLE_URI_PARSE_ERROR` variable that was never wired up.\n\nConsequences on the error branch:\n\n- `ARGS_GET` / `ARGS_GET_NAMES` / `ARGS` (union) are **empty** \u2014 `ExtractGetArguments` is never called.\n- `QUERY_STRING` is **empty** (initial `query := \"\"` at line 835 persists through to `queryString.Set(query)` at line 866).\n- `REQUEST_FILENAME` / `REQUEST_BASENAME` contain the entire URI including any `?\u2026` query suffix (because `path = uri` at line 838 bypasses the parse, and the subsequent `strings.LastIndexAny(path, \"/\\\\\")` runs over the raw URI).\n- `URLENCODED_ERROR` is set to the Go error message. That variable is *also* set by the urlencoded body processor on body-decode failures, so an operator cannot distinguish \"malformed URI\" from \"malformed request body\" without string-matching the error text.\n- `REQUEST_URI_RAW` (set unconditionally at line 822, before the parse) **is** populated correctly.\n\nAny rule targeting `ARGS_GET`, `ARGS`, `ARGS_NAMES`, `ARGS_GET_NAMES`, or `QUERY_STRING` \u2014 which is the default target set for the vast majority of OWASP CRS GET-side signature rules \u2014 does not fire against attacker content that reaches Coraza via a URI Go\u0027s `net/url` rejects.\n\n## Reachability\n\nThis issue **does not affect the standard `coraza/v3/http` + `net/http` integration**. Go\u0027s `http.ReadRequest` calls `url.ParseRequestURI` first and rejects malformed URIs with `400 Bad Request` before `ProcessURI` is invoked. Verified experimentally against a Coraza-wrapped `net/http` server \u2014 a raw request with a control-byte-laced URI produced `HTTP 400`, and the handler was never reached.\n\nThe bug is reachable when an integration forwards raw URI bytes to `tx.ProcessURI` directly, bypassing Go\u0027s HTTP parser:\n\n- **`coraza-spoa`** \u2014 HAProxy SPOP agent. Receives URI from HAProxy, which permits bytes `net/http` rejects.\n- **`coraza-proxy-wasm`** \u2014 Envoy WASM filter. Passes the `:path` pseudo-header from Envoy.\n- Custom FFI/WASM hosts and any embedder calling `tx.ProcessURI(rawURI, method, httpVersion)` with bytes not pre-validated by Go\u0027s URL parser.\n\nThis gates the attack to Attack Complexity:High \u2014 a standard Go HTTP deployment is not exposed.\n\n## Proof of Concept\n\nDirect-API reproduction (simulating the non-net/http integration path):\n\n```go\nwaf, _ := coraza.NewWAF(coraza.NewWAFConfig().WithDirectives(`\nSecRuleEngine On\nSecRule ARGS_GET     \"@contains ATTACK_HERE_XYZ\" \"id:9001,phase:1,deny,status:403\"\nSecRule QUERY_STRING \"@contains ATTACK_HERE_XYZ\" \"id:9002,phase:1,deny,status:403\"\n`))\n\nfor _, uri := range []string{\n    \"/search?q=ATTACK_HERE_XYZ\",                    // baseline\n    \"/search?q=ATTACK_HERE_XYZ\\x00\u0026y=1\",            // NUL byte\n    \"/search?q=ATTACK_HERE_XYZ\\ninjected: header\",  // bare LF\n    \"/search?q=ATTACK_HERE_XYZ\\rhdr: x\",            // bare CR\n    \"/search?q=ATTACK_HERE_XYZ\\tx=1\",               // tab\n} {\n    tx := waf.NewTransaction()\n    tx.ProcessURI(uri, \"GET\", \"HTTP/1.1\")\n    it := tx.ProcessRequestHeaders()\n    // inspect tx.Variables().QueryString().Get() and tx.Variables().ArgsGet().FindAll()\n    tx.Close()\n}\n```\n\nObserved:\n\n| URI | `QUERY_STRING` | `ARGS_GET` | interrupted? |\n|---|---|---|---|\n| `/search?q=ATTACK_HERE_XYZ` | `q=ATTACK_HERE_XYZ` | 1 entry | **yes (403)** |\n| `/search?q=ATTACK_HERE_XYZ\\x00\u0026y=1` | `\"\"` | 0 entries | **no \u2014 BYPASS** |\n| `/search?q=ATTACK_HERE_XYZ\\ninjected: header` | `\"\"` | 0 entries | **no \u2014 BYPASS** |\n| `/search?q=ATTACK_HERE_XYZ\\rhdr: x` | `\"\"` | 0 entries | **no \u2014 BYPASS** |\n| `/search?q=ATTACK_HERE_XYZ\\tx=1` | `\"\"` | 0 entries | **no \u2014 BYPASS** |\n\n`REQUEST_URI_RAW` is populated correctly in every case (line 822 sets it before the parse), so a rule written against `REQUEST_URI_RAW` still catches the attack. CRS and most operator-written rules target `ARGS_GET` / `ARGS` / `QUERY_STRING` \u2014 those do not fire.\n\nHTTP-layer reachability check (stock `net/http`):\n\n```\n$ printf \u0027GET /?q=ATTACK_HERE_XYZ\\x00\u0026y=1 HTTP/1.1\\r\\nHost: x\\r\\n\\r\\n\u0027 | nc 127.0.0.1 8092\nHTTP/1.1 400 Bad Request\n```\n\nConfirms the exposure is limited to non-net/http integrations.\n\n## Mitigation\n\nRecommended fixes, in order:\n\n### 1. Re-enable the existing fallback and wire up `URI_PARSE_ERROR`\n\nThe code to fix this is already present as a commented-out block at `transaction.go:840\u2013851`. Re-enable it, promote the referenced `VARIABLE_URI_PARSE_ERROR` to a real transaction variable, and populate `ARGS_GET` / `QUERY_STRING` from the raw `?\u2026` tail:\n\n```go\nif err != nil {\n    tx.variables.urlencodedError.Set(err.Error())\n    tx.variables.uriParseError.Set(\"1\")               // new variable\n    tx.variables.requestURI.Set(uri)\n    if i := strings.Index(uri, \"?\"); i != -1 {\n        path = uri[:i]\n        query = uri[i+1:]\n        tx.ExtractGetArguments(query)                  // populate ARGS_GET\n    } else {\n        path = uri\n    }\n} else {\n    ...\n}\n```\n\n### 2. Ship a companion rule in `coraza.conf-recommended`\n\n```conf\nSecRule URI_PARSE_ERROR \"@eq 1\" \\\n    \"id:\u0027200010\u0027,phase:1,t:none,log,deny,status:400,msg:\u0027URI failed to parse\u0027\"\n```\n\nThis gives operators a fail-closed default (analogous to rule 200003 for multipart strict error and rule 200002 for body-parse error), so non-net/http integrations at least stop the request regardless of downstream rule coverage.\n\n### 3. Do not overload `URLENCODED_ERROR`\n\nThe current code uses `URLENCODED_ERROR` for URI parse failures. That variable is also set by the urlencoded body processor on body-decode errors; operators cannot distinguish the two causes without string-matching the error text, and any rule they add will fire on both classes of failure. A dedicated `URI_PARSE_ERROR` variable (per the commented-out TODO) is the right shape.\n\n## Affected versions\n\nAll releases on the v3 branch (`\u003e= 3.0.0, \u003c= 3.7.0`); the silent-drop behavior has been present since the first v3 release. Only deployments using non-net/http integrations (coraza-spoa, coraza-proxy-wasm, custom FFI) are exposed in practice.\n\n## References\n\n- `internal/corazawaf/transaction.go` lines 834\u2013866 (ProcessURI error branch)\n- `internal/corazawaf/transaction.go` line 822 (`REQUEST_URI_RAW` is populated before the parse, which is why `REQUEST_URI_RAW`-targeted rules still catch the attack)\n- Commented-out fallback at lines 840\u2013851 referencing `VARIABLE_URI_PARSE_ERROR`\n- CWE-20 \u2014 Improper Input Validation\n- CWE-436 \u2014 Interpretation Conflict\n\n### Severity (revised 2026-10-02)\n\n`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N` (4.0, Medium).\n\nAttack Complexity stays High: the bypass only applies to integrations that pass Coraza a raw URI that Go\u0027s URL parser rejects, which `net/http` does not. The previous vector scored Integrity High (6.8); it is scored here like Coraza\u0027s other inspection bypasses.\n\nImpact metrics follow the convention used across Coraza\u0027s WAF-bypass advisories: the vulnerable component is Coraza, but the impact lands on the protected application, so Scope is Changed. The bypass hides a payload from inspection; the application still has to be vulnerable to it, so Integrity is Low and Confidentiality is not scored separately.\n\n_AI involvement in this section: Claude Opus 5.5 (Anthropic), via Claude Code, re-derived the CVSS vector from the project\u0027s triage guidance (AGENTS.md, \"CVSS preconditions get verified, not copied from the report\") and drafted this text. A human maintainer (fzipi) chose the `S:C/I:L` impact convention and directed this update._",
  "id": "GHSA-x26q-wvhg-fh4m",
  "modified": "2026-10-09T17:32:28Z",
  "published": "2026-10-08T17:46:00Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/corazawaf/coraza/security/advisories/GHSA-x26q-wvhg-fh4m"
    },
    {
      "type": "WEB",
      "url": "https://github.com/corazawaf/coraza/commit/0321af96cef18fbafb40980cf075d7cc449a66fa"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/corazawaf/coraza"
    },
    {
      "type": "WEB",
      "url": "https://github.com/corazawaf/coraza/releases/tag/v3.8.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Coraza: ProcessURI silently drops QUERY_STRING and ARGS_GET on URI parse failure \u2014 defense-in-depth bypass for non-net/http integrations"
}



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