Use After Free Affecting pycares package, versions [,4.9.0)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-PYTHON-PYCARES-10365309
- published17 Jun 2025
- disclosed16 Jun 2025
- creditvEpiphyte
Introduced: 16 Jun 2025
NewCVE-2025-48945 (opens in a new tab)How to fix?
Upgrade pycares to version 4.9.0 or higher.
Overview
Affected versions of this package are vulnerable to Use After Free via improper handling of callback references during the destruction of the Channel object. An attacker can cause a fatal interpreter crash by triggering DNS queries that result in the Channel object being garbage collected before the queries complete. This is particularly problematic in scenarios where:
- Channel objects are created per-request
- Multiple failed DNS queries are processed rapidly
- The application doesn't properly manage Channel lifecycle
Note: This issue is much more likely to occur when using event_thread=True but could happen without it under the right circumstances.