CVE-2023-52426

Denial of service via recursive entity expansion

Published Feb 4, 2024 · Updated Nov 4, 2025

XML entity expansion in libexpat 2.5.0 and earlier allows attackers to interrupt service by parsing crafted XML. In xmlparse.c, compile-time XML_DTD guards omit amplification accounting and limit enforcement even when general entities remain enabled. Only uncommon builds with XML_DTD undefined are exposed, and uncontrolled entity growth can exhaust resources in the consuming process.

CVSS severity5.5
Medium
EPSS probability0.37%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

XML entity expansion in libexpat 2.5.0 and earlier allows attackers to interrupt service by parsing crafted XML. In xmlparse.c, compile-time XML_DTD guards omit amplification accounting and limit enforcement even when general entities remain enabled. Only uncommon builds with XML_DTD undefined are exposed, and uncontrolled entity growth can exhaust resources in the consuming process.

The record

CVE
CVE-2023-52426
Published
Feb 4, 2024
Updated
Nov 4, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-776, CAPEC-197, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 4, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5CISA-ADPCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.3Amazon LinuxCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
5.1IBM X-ForceCVSS:3.0/AV:L/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-776Improper Restriction of Recursive Entity References in DTDs ('XML Entity Expansion')
CAPEC-197Exponential Data Expansion
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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