CVE-2023-43669Public exploitNetwork attack vector

Service interruption via repeated oversized-header parsing

Published Sep 21, 2023 · Updated Aug 2, 2024

Denial of service in Tungstenite 0.20.0 and earlier allows remote attackers to interrupt WebSocket servers via an oversized HTTP header. The server handshake machine reparses an ever-growing buffer on each read, so one long header drives thousands of parses over millions of bytes. Any unauthenticated client that can reach a Tungstenite-backed WebSocket listener can monopolize CPU for minutes before the protocol upgrade.

CVSS severity7.5
High
EPSS probability1.62%
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 Tungstenite 0.20.0 and earlier allows remote attackers to interrupt WebSocket servers via an oversized HTTP header. The server handshake machine reparses an ever-growing buffer on each read, so one long header drives thousands of parses over millions of bytes. Any unauthenticated client that can reach a Tungstenite-backed WebSocket listener can monopolize CPU for minutes before the protocol upgrade.

The record

CVE
CVE-2023-43669
Published
Sep 21, 2023
Updated
Aug 2, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-400, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 21, 2023CVE publishedPublication date reported by the CVE source.
  2. Aug 2, 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

7.5GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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 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 exploitPublished

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
T1499.004Application or System Exploitation

Public exploit references

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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