CVE-2016-10228 in C Library
Summary
by MITRE
The iconv program in the GNU C Library (aka glibc or libc6) 2.25 and earlier, when invoked with the -c option, enters an infinite loop when processing invalid multi-byte input sequences, leading to a denial of service.
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Analysis
by VulDB Data Team • 10/01/2025
The vulnerability identified as CVE-2016-10228 represents a critical denial of service flaw within the GNU C Library implementation of the iconv utility. This issue affects glibc versions 2.25 and earlier, where the iconv program exhibits problematic behavior when processing invalid multi-byte input sequences through the -c command-line option. The flaw manifests as an infinite loop during input validation, causing system resources to become consumed indefinitely and rendering the affected system unavailable to legitimate users.
The technical root cause of this vulnerability lies in the improper handling of malformed multi-byte character sequences within the iconv implementation. When the -c option is specified, which instructs iconv to continue processing after encountering invalid input rather than terminating, the library fails to properly validate the input sequence boundaries. This leads to a condition where the processing loop continues indefinitely, continuously checking the same invalid input without making progress toward completion. The flaw operates at the core level of character encoding conversion, where the library's state machine for handling multi-byte sequences becomes trapped in a recursive validation pattern that never reaches a termination condition.
From an operational impact perspective, this vulnerability presents a significant risk to systems that rely on glibc for character encoding conversion operations. Attackers can exploit this flaw by providing specifically crafted invalid multi-byte input sequences to any application that invokes iconv with the -c option, potentially causing the target process to consume excessive CPU resources or become unresponsive entirely. The infinite loop behavior effectively creates a denial of service condition that can be triggered remotely through any interface that utilizes iconv for text processing, including web applications, network services, and system utilities that perform character encoding conversions. This vulnerability particularly affects systems where iconv is used extensively in text processing pipelines or where applications may be exposed to untrusted input from external sources.
Security practitioners should note that this vulnerability aligns with CWE-835, which describes the weakness of infinite loops or infinite recursion in software implementations. The flaw demonstrates how seemingly benign input validation options can create exploitable conditions when combined with inadequate boundary checking mechanisms. Organizations should prioritize updating to glibc version 2.26 or later, which contains the necessary patches to prevent the infinite loop behavior. Additionally, system administrators should implement monitoring for unusual CPU consumption patterns that might indicate exploitation attempts. The ATT&CK framework categorizes this as a denial of service attack vector through resource exhaustion, where the infinite loop serves as the exploitation mechanism. Mitigation strategies should include input sanitization at application layers, implementing timeouts for character conversion operations, and ensuring all systems maintain current glibc versions to prevent exploitation of this and related vulnerabilities.