HTTP.sys Denial of Service Vulnerability
Uncontrolled resource consumption in HTTP/2 allows an unauthorized attacker to deny service over a network.
- Published
- Jun 9, 2026
- Updated
- Sep 24, 2026
- EPSS
- 1.2% · 66th percentile
- CWE
- CWE-400
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Report tools
Action score
30
Monitor
Low priority for now.
- CVSS
- 30 / 40 · 7.5 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 1.2%
CISA SSVC decision
- Exploitation
- none
- Automatable
- yes
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- —
- CNA · microsoft
- 7.5
- NVD has not scored this yet; the score shown is the CNA’s.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for the hundreds of thousands of vulnerabilities in the database; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpAffected systems
| Vendor | Product | CPE |
|---|---|---|
| microsoft | windows 10 1607 | cpe:2.3:o:microsoft:windows_10_1607 |
| microsoft | windows 10 1809 | cpe:2.3:o:microsoft:windows_10_1809 |
| microsoft | windows 10 21h2 | cpe:2.3:o:microsoft:windows_10_21h2 |
| microsoft | windows 10 22h2 | cpe:2.3:o:microsoft:windows_10_22h2 |
| microsoft | windows 11 23h2 | cpe:2.3:o:microsoft:windows_11_23h2 |
| microsoft | windows 11 24h2 | cpe:2.3:o:microsoft:windows_11_24h2 |
| microsoft | windows 11 25h2 | cpe:2.3:o:microsoft:windows_11_25h2 |
| microsoft | windows 11 26h1 | cpe:2.3:o:microsoft:windows_11_26h1 |
| microsoft | windows server 2016 | cpe:2.3:o:microsoft:windows_server_2016 |
| microsoft | windows server 2019 | cpe:2.3:o:microsoft:windows_server_2019 |
| microsoft | windows server 2022 | cpe:2.3:o:microsoft:windows_server_2022 |
| microsoft | windows server 2025 | cpe:2.3:o:microsoft:windows_server_2025 |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- microsoft windows server 2016before 10.0.14393.9234
- microsoft windows server 2019before 10.0.17763.8880
- microsoft windows server 2022before 10.0.20348.5256
- microsoft windows server 2025before 10.0.26100.32995
Versions reported by the vendor
Affected version ranges reported by the assigning authority (microsoft). Independent of NVD's CPE analysis and usually ahead of it.
Microsoft Windows 10 Version 1607
- 10.0.14393.0 and later · before 10.0.14393.9234affected
Microsoft Windows 10 Version 1809
- 10.0.17763.0 and later · before 10.0.17763.8880affected
Microsoft Windows 10 Version 21H2
- 10.0.19044.0 and later · before 10.0.19044.7417affected
Microsoft Windows 10 Version 22H2
- 10.0.19045.0 and later · before 10.0.19045.7417affected
Microsoft Windows 11 version 23H2
- 10.0.22631.0 and later · before 10.0.22631.7219affected
Microsoft Windows 11 Version 23H2
- 10.0.22631.0 and later · before 10.0.22631.7219affected
Microsoft Windows 11 Version 24H2
- 10.0.26100.0 and later · before 10.0.26100.8655affected
Microsoft Windows 11 Version 25H2
- 10.0.26200.0 and later · before 10.0.26200.8655affected
Microsoft Windows 11 version 26H1
- 10.0.28000.0 and later · before 10.0.28000.2269affected
Microsoft Windows Server 2016
- 10.0.14393.0 and later · before 10.0.14393.9234affected
Microsoft Windows Server 2016 (Server Core installation)
- 10.0.14393.0 and later · before 10.0.14393.9234affected
Microsoft Windows Server 2019
- 10.0.17763.0 and later · before 10.0.17763.8880affected
Same product
microsoft: all recordsOther highest-scoring records for the same primary product.
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- CVE-2026-21510Windows Shell Security Feature Bypass VulnerabilityKEV72This week
- CVE-2026-21513MSHTML Framework Security Feature Bypass VulnerabilityKEV70This week
- CVE-2023-24880Windows SmartScreen Security Feature Bypass VulnerabilityKEV70This week
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Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
No fix version is recorded for this entry. Check the references for vendor advisories.
Exploit status
Proof of concept available
A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.
Evidence
- Proof-of-concept repository on GitHub ×1
Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.
| Source | Kind | Date |
|---|---|---|
| Proof-of-concept repository on GitHub | stars:5 | 2026-06-15 |
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
- Published
- First PoC+5 d
- TodayOct 2, 2026+115 d
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
- CVE-2026-8396891 days apartWindows Biometric Service Elevation of Privilege Vulnerability31Monitor
- CVE-2025-21351483 days apartWindows Active Directory Domain Services API Denial of Service Vulnerability31Monitor
- CVE-2026-5862735 days apartWindows DHCP Server Denial of Service Vulnerability30Monitor
- CVE-2026-4979935 days apartWindows Local Security Authority Subsystem Service (LSASS) Denial of Service Vulnerability26Monitor
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- none
- Integrity
- none
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- None
- Integrity impact
- None
- Availability impact
- High
Weakness class (CWE)
CWE-400 · Uncontrolled Resource ConsumptionCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
nvd-secondary
Root cause
Code that parses nested structures sets no depth or size limit. A small input can turn into a disproportionate processing load.
The bug in code
The whole CWE-400 classA representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.
Vulnerable
function expand(node) { return node.children.map(expand);}Fixed
const MAX_DEPTH = 32;function expand(node, depth = 0) { if (depth > MAX_DEPTH) throw new Error("too deep"); return node.children.map((c) => expand(c, depth + 1));}Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Change log
No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.
References
Vendor advisories and official records. Exploit/PoC links are deliberately left out.