CVE-2018-11033 in Xpdf
Summary
by MITRE
The DCTStream::readHuffSym function in Stream.cc in the DCT decoder in xpdf before 4.00 allows remote attackers to cause a denial of service (application crash) or possibly have unspecified other impact via crafted JPEG data.
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Analysis
by VulDB Data Team • 03/07/2025
The vulnerability identified as CVE-2018-11033 resides within the DCTStream::readHuffSym function in the Stream.cc file of the xpdf DCT decoder component. This flaw affects versions of xpdf prior to 4.00 and represents a critical security issue that can be exploited through crafted JPEG data. The vulnerability stems from inadequate input validation and error handling within the JPEG decoding process, specifically when processing Huffman-coded data streams that are part of the Discrete Cosine Transform decoding functionality. The issue manifests as a potential application crash or unspecified other impacts when the decoder encounters malformed or maliciously constructed JPEG data structures.
The technical nature of this vulnerability places it within the category of buffer over-read or improper input validation flaws, which can be classified under CWE-129 and CWE-704 according to the Common Weakness Enumeration standards. The DCTStream::readHuffSym function processes Huffman symbols during JPEG decompression, and when it encounters malformed data, it fails to properly validate the input before attempting to read from memory locations that may be outside the expected bounds. This can lead to memory corruption and subsequent application instability or complete crash, effectively creating a denial of service condition. The vulnerability operates at the intersection of image processing and memory management, where the JPEG decoder's failure to properly validate Huffman table entries or symbol lengths creates exploitable conditions.
From an operational perspective, this vulnerability presents significant risks to systems that process or render JPEG images, particularly in environments where untrusted input is handled. The impact extends beyond simple denial of service to potentially encompass arbitrary code execution or information disclosure, depending on the specific memory corruption patterns and system configurations. Attackers can craft malicious JPEG files that, when processed by vulnerable xpdf implementations, trigger the flaw and cause the application to crash or behave unpredictably. This makes the vulnerability particularly dangerous in web applications, document processing systems, or any environment where JPEG files from untrusted sources are automatically processed or rendered.
Mitigation strategies for CVE-2018-11033 primarily involve upgrading to xpdf version 4.00 or later, which contains the necessary patches to address the input validation issues in the DCT decoder. Organizations should also implement input sanitization measures for JPEG data, particularly in web applications or document processing pipelines, where the vulnerability could be exploited through user-uploaded content. Additional defensive measures include deploying network-based intrusion detection systems that can identify and block suspicious JPEG data patterns, implementing strict file format validation, and utilizing sandboxing techniques to isolate JPEG processing operations. The ATT&CK framework categorizes this vulnerability under the T1203 - Exploitation for Client Execution tactic, as it represents a classic client-side exploitation vector that leverages image processing libraries to achieve system compromise. Security teams should also consider implementing automated patch management processes to ensure all systems utilizing xpdf or related components remain protected against this and similar vulnerabilities.