CVE-2023-31130

Process crash via IPv6 prefix buffer underwrite

Published May 25, 2023 · Updated Feb 13, 2025

Buffer underwrite in c-ares before 1.19.1 allows local users to crash a consuming process via a crafted IPv6 network prefix. In ares_inet_net_pton(), the IPv6 parser shortens its temporary buffer endpoint from the prefix length, then shifts more parsed bytes than fit and writes before the buffer. Internal reachability requires an administrator-supplied sort-list entry through ares_set_sortlist(); direct API consumers expose the same memory corruption to input paths they control.

CVSS severity4.1
Medium
EPSS probability0.39%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Buffer underwrite in c-ares before 1.19.1 allows local users to crash a consuming process via a crafted IPv6 network prefix. In ares_inet_net_pton(), the IPv6 parser shortens its temporary buffer endpoint from the prefix length, then shifts more parsed bytes than fit and writes before the buffer. Internal reachability requires an administrator-supplied sort-list entry through ares_set_sortlist(); direct API consumers expose the same memory corruption to input paths they control.

The record

CVE
CVE-2023-31130
Published
May 25, 2023
Updated
Feb 13, 2025
Vendor
c-ares Project
Product
c-ares
Classifications
CWE-124, T1499.004
Attack vector
local
Privileges
admin

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 vectorlocal
Required privilegesadmin

What is affected?

c-ares Project · c-aresversion=< 1.19.1

Published CVSS scores

4.1GitHub, Inc.CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H
6.4NISTCVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-124Buffer Underwrite ('Buffer Underflow')
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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