Skip to main content
VulnerabilityPublished

CVE-2025-48945: aio-libs aiodns · Use After Free

Affects aio-libs aiodnsSource CVE Database V5

0

Not known to be exploited · CVSS 8.2 High : upgrade to 4.9.0 soon.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 4.0 base score
8.2High
How severe the flaw is on the 0–10 CVSS scale.
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:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 21 Jun 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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

ProductAffectedFixed in
PyPIpycarespkg:pypi/pycaresOther threatsAffected
  • <4.9.0
Fixed in
  • 4.9.0

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

Community reviews

Loading reviews…