CVE-2025-48945: aio-libs aiodns · Use After Free
Affects aio-libs aiodnsSource CVE Database V5
Not known to be exploited · CVSS 8.2 High : upgrade to 4.9.0 soon.
Data as of 26 Oct 2026, 14:05 UTC
- EPSS
- 0.4% chance of exploitation in 30 days – higher than 41% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 4.9.0
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 21 Jun 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade pycares to 4.9.0.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
PyPIpycarespkg:pypi/pycaresOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
Upgrade to pycares version 4.9.0 or later, which includes a fix with no required code changes. Optionally, developers should explicitly close Channel objects or use context managers to manage Channel lifecycle safely. Avoid creating Channel objects per-request and prefer long-lived instances for better safety and performance.
Description
CVE-2025-48945 is a use-after-free vulnerability in the pycares library (part of aio-libs aiodns) that occurs when a Channel object is garbage collected while DNS queries are still pending. This leads to a fatal Python interpreter crash due to invalid callback references. The issue arises from a race condition between Python's garbage collector and c-ares callback execution. The vulnerability is fixed in pycares version 4.9.0 with a safe channel destruction mechanism.
References
- github.com/saghul/pycares/security/advisories/GHSA-5qpg-rh4j-qp35 (opens in a new tab)
- github.com/aio-libs/aiodns/commit/f259a6e3650555157af53ac2b39f2ff545321d55 (opens in a new tab)
- github.com/saghul/pycares/commit/ebfd7d71eb8e74bc1057a361ea79a5906db510d4 (opens in a new tab)
- github.com/aio-libs/aiodns/releases/tag/v3.5.0 (opens in a new tab)
- github.com/saghul/pycares/releases/tag/v4.9.0 (opens in a new tab)