T09 · Insecure Skill Coding Practices
- Location
search.py:11- Finding
Unbounded Remote Sitemap Retrieval and Parsing Can Cause Resource Exhaustion
- Content
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Vulnerability Details
File Location:
search.py, lines 11-20
Vulnerability Type: Unbounded network response processing and missing request timeout
Risk Level: Mediumpython def fetch_sitemap(): """Fetches the sitemap from Agnxi.com.""" try: with urllib.request.urlopen(SITEMAP_URL) as response: return response.read() except Exception as e: print(f"Error fetching sitemap: {e}", file=sys.stderr) return None def parse_sitemap(xml_content, query): """Parses sitemap XML and filters based on query.""" try: root = ET.fromstring(xml_content)Technical Analysis
The call to
urllib.request.urlopen()does not specify a timeout, so the process can remain blocked while connecting to or reading from an unresponsive upstream server. In addition,response.read()reads the complete HTTP response into memory without enforcing a maximum size.The resulting attacker-controlled byte sequence is subsequently passed to
ET.fromstring(), which constructs an in-memory XML tree. A very large sitemap can therefore consume substantial memory both as raw response data and as parsed XML objects. Although the fixed HTTPS endpoint limits who can directly supply the response, exploitation is possible if the Agnxi server, domain, or content-delivery infrastructure is compromised or begins serving malformed or oversized content.Attack Path
- An attacker gains control over, or compromises, the configured Agnxi sitemap endpoint or its serving infrastructure.
- The attacker serves the sitemap extremely slowly or returns an excessively large XML document.
- A user or agent invokes
search.py, causingfetch_sitemap()to request the malicious response. - Without a timeout, the connection can block execution indefinitely. Alternatively,
response.read()allocates memory for the entire response. ET.fromstring()performs additional proce ...[truncated 660 chars]
- Remediation
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Remediation Suggestions
- Supply a conservative timeout to
urlopen(), for example:python with urllib.request.urlopen(SITEMAP_URL, timeout=10) as response: - Do not use an unrestricted
response.read(). Read the response incrementally in bounded chunks and abort when a defined maximum sitemap size is exceeded. - Check the
Content-Lengthheader when present, while still enforcing the limit during streaming because that header may be absent or inaccurate. - Validate the response status and expected XML content type before parsing.
- Consider incremental XML parsing to avoid retaining both the complete raw response and the complete parsed tree in memory.
- Apply operating-system or container-level limits for memory, CPU time, and execution duration as defense in depth.
- Return a controlled error when timeout, size, status, content-type, or parsing validation fails.
- Supply a conservative timeout to
