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NVD / CVE Program· CNA mitre

CVE-2003-1564: libxml2, possibly before 2.5.0, does not properly detect recursion during entity expansion, which allows context-dependent attackers to…

MediumCVSS 6.5 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 26/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 1.5% (FIRST EPSS); higher than 75.5% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. A user must open a link or visit a page. No special conditions are required; it is repeatable.
  • Fixed version: libxml2 (Red Hat:enterprise_linux:2.1::as) 0:2.4.19-11.ent; libxml2-devel (Red Hat:enterprise_linux:2.1::as) 0:2.4.19-11.ent; libxml2-python (Red Hat:enterprise_linux:2.1::as) 0:2.4.19-11.ent.

Low priority for now. Upgrade to libxml2 (Red Hat:enterprise_linux:2.1::as) 0:2.4.19-11.ent; libxml2-devel (Red Hat:enterprise_linux:2.1::as) 0:2.4.19-11.ent; libxml2-python (Red Hat:enterprise_linux:2.1::as) 0:2.4.19-11.ent or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

libxml2, possibly before 2.5.0, does not properly detect recursion during entity expansion, which allows context-dependent attackers to cause a denial of service (memory and CPU consumption) via a crafted XML document containing a large number of nested entity references, aka the "billion laughs attack."

Published
Dec 31, 2003
Updated
Jun 16, 2026
EPSS
1.5% · 75th percentile

Report tools

JSON

Action score

26

Monitor

Low priority for now.

CVSS
26 / 40 · 6.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 1.5%

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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Follow CVE-2003-1564

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
xmlsoftlibxml2

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • xmlsoft libxml2before 2.5.0

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Red Hat:enterprise_linux:2.1::aslibxml2before 0:2.4.19-11.ent0:2.4.19-11.ent
Red Hat:enterprise_linux:2.1::aslibxml2-develbefore 0:2.4.19-11.ent0:2.4.19-11.ent
Red Hat:enterprise_linux:2.1::aslibxml2-pythonbefore 0:2.4.19-11.ent0:2.4.19-11.ent

Same product

xmlsoft: all records

Other highest-scoring records for the same primary product.

  • CVE-2008-3529Heap-based buffer overflow in the xmlParseAttValueComplex function in parser.c in libxml2 before 2.7.0 allows context-dependent attackers…
    47Plan
  • CVE-2017-7376Buffer overflow in libxml2 allows remote attackers to execute arbitrary code by leveraging an incorrect limit for port values when handling…
    46Plan
  • CVE-2022-40303An issue was discovered in libxml2 before 2.10.3.
    42Plan

Published before and after this one in the same product

  • Later →CVE-2008-3281Aug 27, 2008 · libxml2 2.6.32 and earlier does not properly detect recursion during entity expansion in an attribute value, which allows context-dependent…
    27Monitor
  • Later →CVE-2008-4409Oct 3, 2008 · libxml2 2.7.0 and 2.7.1 does not properly handle "predefined entities definitions" in entities, which allows context-dependent attackers to…
    23Monitor
  • Later →CVE-2011-1944Sep 2, 2011 · Integer overflow in xpath.c in libxml2 2.6.x through 2.6.32 and 2.7.x through 2.7.8, and libxml 1.8.16 and earlier, allows…
    41Plan

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
red hat:libxml20:2.4.19-11.ent · Red Hat:enterprise_linux:2.1::asPackage registry (OSV)
red hat:libxml2-devel0:2.4.19-11.ent · Red Hat:enterprise_linux:2.1::asPackage registry (OSV)
red hat:libxml2-python0:2.4.19-11.ent · Red Hat:enterprise_linux:2.1::asPackage registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · variant or chain candidate · public bounty program.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • A user must open a link or visit a page.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
Required
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-776 · Improper Restriction of Recursive Entity References in DTDs ('XML Entity Expansion')

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

References

Show all references (5 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records