CVE-2020-11080Network attack vector

Service interruption via unlimited SETTINGS frame processing

Published Jun 3, 2020 · Updated Jun 9, 2025

Denial of service in nghttp2 before 1.41.0 allows remote attackers to saturate a server's CPU through repeated oversized SETTINGS frames. The HTTP/2 session parser derives the entry count from frame length and allocates and processes every SETTINGS entry without a limit. An unauthenticated client must repeatedly send a 14,400-byte frame containing 2,400 entries, driving CPU use to 100% and interrupting service.

CVSS severity7.5
High
EPSS probability5.32%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in nghttp2 before 1.41.0 allows remote attackers to saturate a server's CPU through repeated oversized SETTINGS frames. The HTTP/2 session parser derives the entry count from frame length and allocates and processes every SETTINGS entry without a limit. An unauthenticated client must repeatedly send a 14,400-byte frame containing 2,400 entries, driving CPU use to 100% and interrupting service.

The record

CVE
CVE-2020-11080
Published
Jun 3, 2020
Updated
Jun 9, 2025
Vendor
nghttp2
Product
nghttp2
Classifications
CWE-400, CWE-707, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 3, 2020CVE publishedPublication date reported by the CVE source.
  2. Jun 9, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 1.41.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

nghttp2 · nghttp2version=< 1.41.0

Published CVSS scores

7.5NISTCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.7GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
5.0NISTAV:N/AC:L/Au:N/C:N/I:N/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
CWE-707Improper Neutralization
T1499.004Application or System Exploitation Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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