CVE-2017-9233
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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (8.74%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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.
- CVSS 3.1
- 7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 8.74% probability · 95th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-611, CWE-835
- Affected
- libexpat project/libexpat · python/python · debian/debian linux
- Source
- cve@mitre.org
EPSS 8.7% since 27 October 2026; no change recorded yet. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- http://www.debian.org/security/2017/dsa-3898Third Party Advisory
- http://www.openwall.com/lists/oss-security/2017/06/17/7Mailing List, VDB Entry
- http://www.securityfocus.com/bid/99276Third Party Advisory, VDB Entry
- http://www.securitytracker.com/id/1039427Third Party Advisory, VDB Entry
- https://github.com/libexpat/libexpat/blob/master/expat/ChangesRelease Notes, Third Party Advisory
- https://libexpat.github.io/doc/cve-2017-9233/Exploit, Technical Description, Vendor Advisory
- 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/HT208112Third Party Advisory
- https://support.apple.com/HT208113Third Party Advisory
- https://support.apple.com/HT208115Third Party Advisory
- https://support.apple.com/HT208144Third Party Advisory
- https://support.f5.com/csp/article/K03244804Third Party Advisory
- http://www.debian.org/security/2017/dsa-3898Third Party Advisory
- http://www.openwall.com/lists/oss-security/2017/06/17/7Mailing List, VDB Entry
- http://www.securityfocus.com/bid/99276Third Party Advisory, VDB Entry
- http://www.securitytracker.com/id/1039427Third Party Advisory, VDB Entry
- https://github.com/libexpat/libexpat/blob/master/expat/ChangesRelease Notes, Third Party Advisory
- https://libexpat.github.io/doc/cve-2017-9233/Exploit, Technical Description, Vendor Advisory
- 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/HT208112Third Party Advisory
- https://support.apple.com/HT208113Third Party Advisory
- https://support.apple.com/HT208115Third Party Advisory
- https://support.apple.com/HT208144Third Party Advisory
- https://support.f5.com/csp/article/K03244804Third Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.