What’s Vulnerable › Vulnerabilities

CVE-2017-9233

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 8.7% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2017-07-25 · updated 2026-10-08
• Weakness: CWE-611

Description

XML External Entity vulnerability in libexpat 2.2.0 and earlier (Expat XML Parser Library) allows attackers to put the parser in an infinite loop using a malformed external entity definition from an external DTD.

Affected products

• Debian Linux: 8.0, 9.0, 10.0
• libexpat project libexpat: through 2.2.0
• Python: from 2.7.0 before 2.7.15; from 3.3.0 before 3.3.7; from 3.4.0 before 3.4.7; from 3.5.0 before 3.5.4; from 3.6.0 before 3.6.2 — fixed in 2.7.15, 3.3.7, 3.4.7, 3.5.4, 3.6.2

How to fix

Upgrade to a fixed version: Python 2.7.15, 3.3.7, 3.4.7, 3.5.4. Check the vendor advisory for mitigations.

References

• http://www.debian.org/security/2017/dsa-3898
• http://www.openwall.com/lists/oss-security/2017/06/17/7
• http://www.securityfocus.com/bid/99276
• http://www.securitytracker.com/id/1039427
• https://github.com/libexpat/libexpat/blob/master/expat/Changes
• https://libexpat.github.io/doc/cve-2017-9233/
• https://lists.apache.org/thread.html/r58af02e294bd07f487e2c64ffc0a29b837db5600e33b6e698b9d696b%40%3Cissues.bookkeeper.apache.org%3E
• https://lists.apache.org/thread.html/rf4c02775860db415b4955778a131c2795223f61cb8c6a450893651e4%40%3Cissues.bookkeeper.apache.org%3E
• https://support.apple.com/HT208112
• https://support.apple.com/HT208113
• https://support.apple.com/HT208115
• https://support.apple.com/HT208144

Get alerted when CVE-2017-9233 or the next vulnerability affects your stack