CVE-2023-29483Network attack vector

DNS resolution disruption via malformed UDP reply

Published Apr 11, 2024 · Updated Nov 4, 2025

Denial of service in Eventlet before 0.35.2 allows remote attackers to disrupt DNS resolution with a forged malformed UDP reply. The UDP resolver in eventlet/support/greendns.py accepts a response from the expected address and port, then stops on parsing or response-validation errors instead of continuing to listen for a valid answer. Exploitation requires winning a timing race against the legitimate DNS response; successful attempts can make the affected lookup fail or switch resolvers, without reported data disclosure or modification.

CVSS severity5.9
Medium
EPSS probability1.86%
Next 30 days · Sep 17, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Eventlet before 0.35.2 allows remote attackers to disrupt DNS resolution with a forged malformed UDP reply. The UDP resolver in eventlet/support/greendns.py accepts a response from the expected address and port, then stops on parsing or response-validation errors instead of continuing to listen for a valid answer. Exploitation requires winning a timing race against the legitimate DNS response; successful attempts can make the affected lookup fail or switch resolvers, without reported data disclosure or modification.

The record

CVE
CVE-2023-29483
Published
Apr 11, 2024
Updated
Nov 4, 2025
Vendor
Eventlet
Product
Eventlet
Classifications
CWE-696, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 11, 2024CVE publishedPublication date reported by the CVE source.
  2. Nov 4, 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=0 <0.35.2
  2. Affected versionversion=0 <2.6.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Eventlet · Eventletversion=0 <0.35.2; version=0 <2.6.0

Published CVSS scores

5.9GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:H/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.

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

No observations available

Sep 11, 2026Sep 17, 2026
Latest reporting daySep 17, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-696Incorrect Behavior Order
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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