CVE-2011-1754 in jabberd14
Summary
by MITRE
jabberd14 1.6.1.1 and earlier does not properly detect recursion during entity expansion, which allows remote attackers to cause a denial of service (memory and CPU consumption) via a crafted XML document containing a large number of nested entity references, a similar issue to CVE-2003-1564.
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Analysis
by VulDB Data Team • 11/13/2021
The vulnerability described in CVE-2011-1754 affects jabberd14 versions 1.6.1.1 and earlier, specifically targeting the XML processing functionality within the Jabber server implementation. This issue represents a classic example of a denial of service vulnerability that exploits the improper handling of XML entity expansion mechanisms. The flaw resides in the server's inability to effectively detect and prevent recursive entity expansion patterns that could lead to excessive resource consumption. Such vulnerabilities are particularly dangerous in network services as they can be exploited by remote attackers without requiring authentication or special privileges, making them attractive targets for malicious actors seeking to disrupt service availability.
The technical root cause of this vulnerability stems from inadequate recursion detection during XML entity processing. When a crafted XML document contains a large number of nested entity references, the jabberd14 server fails to implement proper safeguards to prevent infinite or excessively deep recursive expansion. This allows an attacker to construct XML payloads that cause the parser to consume excessive memory and CPU resources as it attempts to resolve the nested entity references. The vulnerability is particularly similar to CVE-2003-1564, which established the pattern of XML external entity (XXE) processing flaws that can be exploited for resource exhaustion attacks. The flaw falls under the category of CWE-400, which specifically addresses unchecked resource consumption, and represents a form of XML injection vulnerability that can lead to service disruption.
The operational impact of this vulnerability extends beyond simple denial of service conditions to potentially compromise the entire availability of the Jabber service. Attackers can leverage this weakness to consume system resources at an exponential rate, causing the server to become unresponsive or crash entirely. The memory consumption grows rapidly with each additional level of entity nesting, while CPU utilization spikes as the parser attempts to resolve the recursive references. This type of attack can be particularly devastating in environments where Jabber services are critical for communication infrastructure, as it can effectively shut down messaging capabilities for all users. The vulnerability is especially concerning because it can be exploited through standard XML processing channels without requiring any privileged access or complex exploitation techniques.
Organizations affected by this vulnerability should prioritize immediate patching of their jabberd14 installations to versions that properly implement recursion detection in XML entity processing. The mitigation strategy should include implementing proper XML parser configuration that limits entity expansion depth and prevents excessive resource consumption. Network administrators should also consider implementing rate limiting and resource monitoring mechanisms to detect unusual patterns of entity expansion that could indicate exploitation attempts. From a defensive perspective, this vulnerability aligns with ATT&CK technique T1499.004, which covers network denial of service attacks, and represents a common vector for service disruption attacks that can be automated and scaled across multiple targets. The implementation of proper input validation and XML processing controls should be part of standard security hardening procedures for all XML-based services, particularly those handling untrusted input from external sources.