CVE-2023-31147Network attack vector

DNS response forgery via predictable query IDs

Published May 25, 2023 · Updated Feb 13, 2025

Insufficient randomness in c-ares before 1.19.1 allows remote attackers to forge DNS responses by predicting query identifiers. When preferred entropy sources are unavailable, the query-ID generator passes unseeded rand() output through a noncompliant RC4 implementation. Exploitation requires an attacker able to race a forged reply against the legitimate DNS response, enabling resolution to attacker-chosen addresses.

CVSS severity5.9
Medium
EPSS probability0.91%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Insufficient randomness in c-ares before 1.19.1 allows remote attackers to forge DNS responses by predicting query identifiers. When preferred entropy sources are unavailable, the query-ID generator passes unseeded rand() output through a noncompliant RC4 implementation. Exploitation requires an attacker able to race a forged reply against the legitimate DNS response, enabling resolution to attacker-chosen addresses.

The record

CVE
CVE-2023-31147
Published
May 25, 2023
Updated
Feb 13, 2025
Vendor
c-ares Project
Product
c-ares
Classifications
CWE-330, T1557
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 25, 2023CVE publishedPublication date reported by the CVE source.
  2. Feb 13, 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=< 1.19.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

c-ares Project · c-aresversion=< 1.19.1

Published CVSS scores

6.5NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
5.9GitHub Security AdvisoryCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N

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 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-330Use of Insufficiently Random Values
T1557Adversary-in-the-Middle

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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