CVE-2025-48945: Use-After-Free

Description

pycares is a Python module which provides an interface to c-ares. c-ares is a C library that performs DNS requests and name resolutions asynchronously. Prior to version 4.9.0, pycares is vulnerable to a use-after-free condition that occurs when a Channel object is garbage collected while DNS queries are still pending. This results in a fatal Python error and interpreter crash. The vulnerability has been fixed in pycares 4.9.0 by implementing a safe channel destruction mechanism.

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Weakness Type (CWE)

CWE-416 Use After Free

References

Other References

https://github.com/aio-libs/aiodns/commit/f259a6e3650555157af53ac2b39f2ff545321d55 https://github.com/aio-libs/aiodns/releases/tag/v3.5.0 https://github.com/saghul/pycares/commit/ebfd7d71eb8e74bc1057a361ea79a5906db510d4 https://github.com/saghul/pycares/releases/tag/v4.9.0 https://github.com/saghul/pycares/security/advisories/GHSA-5qpg-rh4j-qp35 https://github.com/saghul/pycares/security/advisories/GHSA-5qpg-rh4j-qp35

Frequently Asked Questions

What is CVE-2025-48945? +

pycares is a Python module which provides an interface to c-ares. c-ares is a C library that performs DNS requests and name resolutions asynchronously. Prior to version 4.9.0, pycares is vulnerable to a use-after-free condition that occurs when a Channel object is garbage collected while DNS queries are still pending. This results in a fatal Python error and interpreter crash. The vulnerability has been fixed in pycares 4.9.0 by implementing a safe channel destruction mechanism.

How do I check if I'm vulnerable to CVE-2025-48945? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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