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Vulnerability record · CVE-2017-11771 · published 13 October 2017

CVE-2017-11771: Windows Search RCE via improper DNS response handling

Microsoft · Windows 10

Microsoft Windows Search fails to properly handle DNS responses, allowing remote code execution. The flaw is an input validation failure (CWE-20) reachable over the network without authentication or user interaction, and it affects a broad set of legacy Windows client and server releases.

9.8 CVSS 3.0 Critical EPSS 52% · top 1.1% CWE-20 · Improper input validation
9.8CVSS 3.0 base score, v2 10.0
52%EPSS exploitation probability, 30 days
NoNot in CISA KEV
7Affected product versions listed by NVD
6References
17 Jun 2026Last modified by NVD

Description

The Microsoft Windows Search component on Microsoft Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8.1, Windows Server 2012 Gold and R2, Windows RT 8.1, Windows 10 Gold, 1511, 1607, and 1703, and Windows Server 2016 allows a remote code execution vulnerability when it fails to properly handle DNS responses, aka "Windows Search Remote Code Execution Vulnerability".

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Automated analysis

Generated by VULONE's analysis model from the NVD record, CISA KEV and EPSS data on 19 September 2026. Confidence: medium.

critical priorityCVSS 3.0 base score is 9.8 with network reachability, no privileges and no user interaction, and EPSS is at the 99.19th percentile.

What it is

Microsoft Windows Search fails to properly handle DNS responses, allowing remote code execution. The flaw is an input validation failure (CWE-20) reachable over the network without authentication or user interaction, and it affects a broad set of legacy Windows client and server releases.

Impact

An unauthenticated remote attacker can execute arbitrary code on the target system, with high impact to confidentiality, integrity and availability.

Attack surface

Reached over the network via DNS responses processed by the Windows Search component; the CVSS vector indicates no privileges and no user interaction required.

Exploitation

Not listed in CISA KEV and no reference carries an exploit tag, but EPSS is high at 0.64132 (99.19th percentile), indicating elevated likelihood of exploitation activity.

What to do

  • Apply the Microsoft security update referenced in the MSRC advisory for CVE-2017-11771.
  • Retire or isolate unsupported legacy platforms (Windows 7 SP1, Windows 8.1, Windows RT 8.1, Server 2008 SP2/R2 SP1, Server 2012/R2) that cannot be patched.
  • Restrict and monitor DNS egress and inbound DNS traffic at network boundaries to limit exposure to malicious responses.
  • Disable or restrict the Windows Search service on systems that do not require it.
  • Segment affected hosts to reduce lateral movement if code execution occurs.

Detection

  • Monitor for unexpected child processes spawned by the Windows Search service (SearchIndexer/SearchProtocolHost).
  • Alert on anomalous DNS response patterns or unusually large or malformed DNS replies reaching Windows hosts.
  • Review Windows event logs and endpoint telemetry for suspicious process creation on affected legacy systems.
  • Track unpatched hosts against the MSRC advisory to confirm remediation coverage.

This assessment is produced automatically and is not human-reviewed. Verify against the vendor advisory before acting on it.

Affected products

7 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
http://www.securityfocus.com/bid/101114 Third Party AdvisoryVDB Entry
http://www.securitytracker.com/id/1039538 Third Party AdvisoryVDB Entry
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2017-11771 PatchVendor Advisory
http://www.securityfocus.com/bid/101114 Third Party AdvisoryVDB Entry
http://www.securitytracker.com/id/1039538 Third Party AdvisoryVDB Entry
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2017-11771 PatchVendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2017-11771), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.