CVE-2021-44716Network attack vector

Remote service interruption via unbounded header cache

Published Jan 1, 2022 · Updated Aug 4, 2024

Uncontrolled memory consumption in Go net/http before 1.16.12 and 1.17.x before 1.17.5 allows remote attackers to exhaust server memory. The http2serverConn.canonicalHeader method caches each attacker-chosen header name in an unbounded per-connection map. An unauthenticated network client must reach an HTTP/2 endpoint; sending many unique header names exhausts process memory and interrupts service.

CVSS severity7.5
High
EPSS probability3.96%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Uncontrolled memory consumption in Go net/http before 1.16.12 and 1.17.x before 1.17.5 allows remote attackers to exhaust server memory. The http2serverConn.canonicalHeader method caches each attacker-chosen header name in an unbounded per-connection map. An unauthenticated network client must reach an HTTP/2 endpoint; sending many unique header names exhausts process memory and interrupts service.

The record

CVE
CVE-2021-44716
Published
Jan 1, 2022
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-400, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 1, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.0NIST NVDAV: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.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 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
T1499.004Application or System Exploitation

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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