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Fencer Vulns
medium 6.5

CVE-2003-1564 json

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

published 2003-12-31 22 y ago modified 2026-06-16 4 mo ago also EUVD-2003-1554

cvss
6.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.6%
EPSS 1.6% chance of exploitation in 30 days, percentile 75%
public exploits
0
none known

Summary

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."

Patch / fix

  • xmlsoft libxml2 2.5.0
  • libxml2 RHEL 2.1 2.4.19-11.ent
  • libxml2-python RHEL 2.1 2.4.19-11.ent

red hat advisories RHSA-2008:0886

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2003-1564 updated

libxml2: billion laughs DoS attack

  • Red Hat Enterprise Linux AS (Advanced Server) version 2.1 libxml2 2.4.19-11.ent, libxml2-python 2.4.19-11.ent Red Hat Enterprise Linux ES version 2.1 libxml2 2.4.19-11.ent, libxml2-python 2.4.19-11.ent Red Hat Enterprise Linux WS version 2.1 libxml2 2.4.19-11.ent, libxml2-python 2.4.19-11.ent Red Hat Linux Advanced Workstation 2.1 libxml2 2.4.19-11.ent, libxml2-python 2.4.19-11.ent
    fixed: vendor fix RHSA-2008:0886

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

1.55% chance of exploitation in the next 30 days, higher than 75% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
NVD 2.0 9.3 AV:N/AC:M/Au:N/C:C/I:C/A:C

Classification

Weakness
  • CWE-776 Improper Restriction of Recursive Entity References in DTDs

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.