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CVE-2026-116566VulnerabilityPublished

host · socket.getaddrinfo() accepts embedded null bytes

Affects MicrosoftSource GCVE Database

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Authoritative record:CVE-2026-116566· Medium 5.3

Not known to be exploited · CVSS 5.3 Medium : upgrade to 3.16.0 when convenient.

Data as of 31 Oct 2026, 08:50 UTC

CVSS 4.0 base score
5.3Medium
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (PSF)CVSS 4.05.3
EPSS
0.2% chance of exploitation in 30 days – higher than 17% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 3.16.0
CVSS:4.0/AV:A/AC:L/AT:P/PR:H/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 29 Oct 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: 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 30 Oct 2026.

What to do

Upgrade CPython to 3.16.0.

Affected software

ProductAffectedFixed in
Python Software FoundationCPythonAffected
  • <3.16.0
Fixed in
  • 3.16.0
GitHubCPythonpkg:github/CPythonOther threatsAffected
  • <3.16.0
Fixed in
  • 3.16.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

Description

A vulnerability identified as CVE-2026-116566 affects Microsoft software version 3.0, where the socket.getaddrinfo() function improperly accepts embedded null bytes in the host and port parameters. This flaw relates to CWE-158, indicating improper handling of input data. No CVSS score or detailed impact information is provided, and there are no known exploits in the wild.

References

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