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Known exploited vulnerability · CISA KEV

CVE-2015-1635: Microsoft HTTP.sys Remote Code Execution Vulnerability

Microsoft HTTP protocol stack (HTTP.sys) contains a vulnerability that allows for remote code execution.

CVE-2015-1635

Exploited in the wild. Fix this first.

CISA added it to the Known Exploited Vulnerabilities catalog on 2022-02-10: attackers are using it right now.

CISA KEV
Listed
Added 2022-02-10 · federal fix-by 2022-08-10
EPSS (30 days)
over 99.9%
Higher than 99.9% of CVEs · 2026-11-01
CVSS v3.1
9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

What CISA says

Microsoft HTTP.sys Remote Code Execution Vulnerability

Apply updates per vendor instructions.

NVD description · published 2015-04-14

HTTP.sys in Microsoft Windows 7 SP1, Windows Server 2008 R2 SP1, Windows 8, Windows 8.1, and Windows Server 2012 Gold and R2 allows remote attackers to execute arbitrary code via crafted HTTP requests, aka "HTTP.sys Remote Code Execution Vulnerability."

Full record on NVD

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How to check if you are exposed to CVE-2015-1635

  1. Find every Microsoft HTTP.sys system you or your clients run, including ones exposed to the internet. Those come first: CISA only lists flaws attackers are already using.
  2. Compare each version with the fixed versions in the vendor advisory. Where no fix exists yet, apply the vendor’s mitigation or take the system off the internet.
  3. Run a credentialed vulnerability scan to catch the systems you missed, then check that the next scan no longer reports CVE-2015-1635.

US federal agencies had to fix this by 2022-08-10. Everyone else should treat that deadline as a guide: if it has passed, this is overdue.

Affected versions

Versions the National Vulnerability Database lists as vulnerable to CVE-2015-1635. Check the vendor advisory for the exact fixed builds before you sign anything off.

ProductVulnerable versions
Microsoft Windows 7--sp1
Microsoft Windows 8all versions
Microsoft Windows 8.1all versions
Microsoft Windows Server 2008r2-sp1
Microsoft Windows Server 2012all versions; r2

Timeline

  1. · Published in the National Vulnerability Database
  2. · Added to CISA's Known Exploited Vulnerabilities catalog, 2,494 days after it was published
  3. · Fix-by date for US federal agencies, passed 1,544 days ago

Weakness type

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CISA lists 390 exploited Microsoft vulnerabilities. The closest matches:

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Sources: CISA Known Exploited Vulnerabilities catalog (version 2026.10.30); EPSS data from FIRST.org; CVSS and descriptions from the NIST National Vulnerability Database. Checked 2026-11-01. This product uses the NVD API but is not endorsed or certified by the NVD.

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