The expat XML parser in the apr_xml_* interface in xml/apr_xml.c in Apache APR-util before 1.3.7, as used in the mod_dav and mod_dav_svn modules in the Apache HTTP Server, allows remote attackers to cause a denial of service (memory consumption) via a crafted XML document containing a large number of nested entity references, as demonstrated by a PROPFIND request, a similar issue to CVE-2003-1564.
Category
The product uses XML documents and allows their structure to be defined with a Document Type Definition (DTD), but it does not properly control the number of recursive definitions of entities.
7.5
CVSS
Severity: High
CVSS 3.1 •
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 2.0 •
AV:N/AC:L/Au:N/C:N/I:N/A:P
EPSS
Probability of exploitation activity in the next 30 days.
CVE-2009-1955 has been scored as a high severity vulnerability.
How to fix CVE-2009-1955?
To fix CVE-2009-1955, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2009-1955 being actively exploited in the wild?
It is possible that CVE-2009-1955 is being exploited or will be exploited in a near future based on public information. According to its EPSS score, there is a ~4% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
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