Affects a core Windows component; critical RCE via network; widespread exposure across Windows servers/desktops.
CVE-2026-47291
RCE via Windows HTTP.sys overflow over the network
Is CVE-2026-47291 being exploited?
Not confirmed. CVE-2026-47291 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 23% probability of exploitation in the next 30 days.
How severe is CVE-2026-47291?
CVE-2026-47291 is rated Critical with a CVSS score of 9.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-47291?
Yes. A fix has been recorded for CVE-2026-47291. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-47291 affect?
CVE-2026-47291 affects Windows HTTP.sys (Windows Server/Windows OS). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-47291?
Apply latest Windows updates; verify HTTP.sys patch status
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Unauthenticated remote code execution via crafted HTTP.sys requests
Immediate action required
- affected>= 10.0.14393.0 and < 10.0.14393.9234
- affected>= 10.0.17763.0 and < 10.0.17763.8880
- affected>= 10.0.19044.0 and < 10.0.19044.7417
- affected>= 10.0.19045.0 and < 10.0.19045.7417
- affected>= 10.0.22631.0 and < 10.0.22631.7219
- affected>= 10.0.22631.0 and < 10.0.22631.7219
- affected>= 10.0.26100.0 and < 10.0.26100.8655
- affected>= 10.0.26200.0 and < 10.0.26200.8655
- affected>= 10.0.28000.0 and < 10.0.28000.2269
- affected>= 6.2.9200.0 and < 6.2.9200.26132
- affected>= 6.3.9600.0 and < 6.3.9600.23228
- affected>= 6.3.9600.0 and < 6.3.9600.23228
- affected>= 6.2.9200.0 and < 6.2.9200.26132
- affected>= 10.0.14393.0 and < 10.0.14393.9234
- affected>= 10.0.14393.0 and < 10.0.14393.9234
- affected>= 10.0.17763.0 and < 10.0.17763.8880
- affected>= 10.0.17763.0 and < 10.0.17763.8880
- affected>= 10.0.20348.0 and < 10.0.20348.5256
- affected>= 10.0.26100.0 and < 10.0.26100.32995
- affected>= 10.0.26100.0 and < 10.0.26100.32995
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.