What’s Vulnerable › Vulnerabilities

CVE-2003-1564

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2003-12-31 · updated 2026-06-16
• Weakness: CWE-776

Description

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."

Affected products

• xmlsoft libxml2: before 2.5.0 — fixed in 2.5.0

How to fix

Upgrade to a fixed version: xmlsoft libxml2 2.5.0. Check the vendor advisory for mitigations.

References

• http://mail.gnome.org/archives/xml/2008-August/msg00034.html
• http://secunia.com/advisories/31868
• http://www.reddit.com/r/programming/comments/65843/time_to_upgrade_libxml2
• http://www.redhat.com/support/errata/RHSA-2008-0886.html
• http://www.stylusstudio.com/xmldev/200302/post20020.html
• http://xmlsoft.org/news.html
• http://mail.gnome.org/archives/xml/2008-August/msg00034.html
• http://secunia.com/advisories/31868
• http://www.reddit.com/r/programming/comments/65843/time_to_upgrade_libxml2
• http://www.redhat.com/support/errata/RHSA-2008-0886.html
• http://www.stylusstudio.com/xmldev/200302/post20020.html
• http://xmlsoft.org/news.html

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