CVE-2025-15282
📋 TL;DR
This vulnerability in Python's urllib.request.DataHandler allows attackers to inject HTTP headers through newline characters in data URL mediatypes. This affects applications that process user-controlled data URLs using Python's urllib library, potentially enabling HTTP request smuggling or header injection attacks.
💻 Affected Systems
- Python
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Attackers could inject arbitrary HTTP headers leading to request smuggling, cache poisoning, or bypassing security controls like authentication headers.
Likely Case
Header injection allowing manipulation of HTTP requests, potentially enabling cross-site request forgery or session hijacking.
If Mitigated
Limited impact if input validation filters newlines or if the application doesn't process untrusted data URLs.
🎯 Exploit Status
Exploitation requires user-controlled input being processed as data URLs through vulnerable code paths.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Python 3.13.2, 3.12.7, 3.11.12, 3.10.14
Vendor Advisory: https://github.com/python/cpython/security/advisories
Restart Required: No
Instructions:
1. Update Python to patched version. 2. For applications: pip install --upgrade python. 3. Restart Python processes to load new version.
🔧 Temporary Workarounds
Input validation filter
allFilter newline characters from user input before processing as data URLs
import re
safe_input = re.sub(r'[\r\n]', '', user_input)
Disable DataHandler
allAvoid using urllib.request.DataHandler for processing untrusted data URLs
# Use alternative URL handling or validate inputs strictly
🧯 If You Can't Patch
- Implement strict input validation to reject data URLs containing newline characters
- Use alternative URL parsing libraries that aren't vulnerable to this specific issue
🔍 How to Verify
Check if Vulnerable:
Check if application processes user-controlled data URLs using urllib.request.DataHandler without newline filteringCheck Version:
python --versionVerify Fix Applied:
Verify Python version is patched and test with malicious data URLs containing newlines📡 Detection & Monitoring
Log Indicators:
- Unusual HTTP headers in requests from data URL sources
- Multiple newline characters in URL parameters
Network Indicators:
- HTTP requests with injected headers from unexpected sources
SIEM Query:
search 'data:' AND ('\n' OR '\r') in url field🔗 References
- https://github.com/python/cpython/commit/05356b1cc153108aaf27f3b72ce438af4aa218c0
- https://github.com/python/cpython/commit/34d76b00dabde81a793bd06dd8ecb057838c4b38
- https://github.com/python/cpython/commit/3f396ca9d7bbe2a50ea6b8c9b27c0082884d9f80
- https://github.com/python/cpython/commit/4ed11d3cd288e6b90196a15c5a825a45d318fe47
- https://github.com/python/cpython/commit/a35ca3be5842505dab74dc0b90b89cde0405017a
- https://github.com/python/cpython/commit/f25509e78e8be6ea73c811ac2b8c928c28841b9f
- https://github.com/python/cpython/issues/143925
- https://github.com/python/cpython/pull/143926
- https://mail.python.org/archives/list/security-announce@python.org/thread/X66HL7SISGJT33J53OHXMZT4DFLMHVKF/
