CVE-2026-62741: Windows HTTP.sys Elevation of Privilege Vulnerability

highCVSS 7.8CVE-2026-62741

Integer underflow (wrap or wraparound) in Windows HTTP.sys allows an authorized attacker to elevate privileges locally.

CSIRTS triage

vendor: Microsoft product: Windows HTTP.sys Privilege escalation

What: Integer underflow in HTTP.sys allowing privilege escalation.
Who is affected: Authorized local attackers on affected Windows systems running HTTP services.
Urgency: High urgency; integer underflow in HTTP.sys with CVSS 7.8 is critical for core HTTP infrastructure.
Action: Apply the latest Windows security patch addressing CVE-2026-62741.

AI-assisted analysis generated from the source advisory — verify against the original.

⚡ Watch Windows HTTP.sys

Get an email when a new Windows HTTP.sys advisory drops — max one per day, one-click unsubscribe.

Details

Source: Microsoft Security Response Center (INTL · vendor-psirt · site)
Severity: high — CVSS 7.8
Published: 2026-08-11
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-62741

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Moderate exploitation riskCVE-2026-627412.0% 30-day exploitation probability. Patch within normal cadence, watch for KEV listing. Riskier than 79% of all EPSS-scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-62741	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

Recent advisories for Windows HTTP.sys Elevation

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

highCVE-2026-62811: Heap-based buffer overflow in Windows HTTP.sys allows an authorized attacker to elevate privil…nvd · 2026-08-11
highCVE-2026-62753: Heap-based buffer overflow in Windows HTTP.sys allows an authorized attacker to elevate privil…nvd · 2026-08-11
highCVE-2026-62741: Integer underflow (wrap or wraparound) in Windows HTTP.sys allows an authorized attacker to el…nvd · 2026-08-11
highCVE-2026-62739: Heap-based buffer overflow in Windows HTTP.sys allows an authorized attacker to elevate privil…nvd · 2026-08-11
highCVE-2026-62735: Heap-based buffer overflow in Windows HTTP.sys allows an authorized attacker to elevate privil…nvd · 2026-08-11
highCVE-2026-61937: Integer overflow or wraparound in Windows HTTP.sys allows an authorized attacker to elevate pr…nvd · 2026-08-11