Remote application crash via freed DNS callbacks
Published Jun 20, 2025 · Updated Jun 20, 2025
Use-after-free in pycares before 4.9.0 allows remote attackers to crash aiodns-dependent Python applications via pending DNS queries. The Channel destructor invalidates ffi.new_handle callback references while c-ares can still invoke them after Python garbage collection. Exploitation requires an application to expose attacker-triggered DNS lookups and discard the Channel before completion; the resulting fatal error terminates that Python process.
Summary
What happened
Use-after-free in pycares before 4.9.0 allows remote attackers to crash aiodns-dependent Python applications via pending DNS queries. The Channel destructor invalidates ffi.new_handle callback references while c-ares can still invoke them after Python garbage collection. Exploitation requires an application to expose attacker-triggered DNS lookups and discard the Channel before completion; the resulting fatal error terminates that Python process.
The record
- CVE
- CVE-2025-48945
- Published
- Jun 20, 2025
- Updated
- Jun 20, 2025
- Vendor
- aio-libs
- Product
- aiodns
- Classifications
- CWE-416, T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 20, 2025CVE publishedPublication date reported by the CVE source.
- Jun 20, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=< 4.9.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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