CVE-2021-29361 in IrfanView
Summary
by MITRE • 09/28/2021
A buffer overflow vulnerability in FORMATS!Read_Utah_RLE+0x340 of Irfanview 4.57 allows attackers to execute arbitrary code via a crafted RLE file.
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Analysis
by VulDB Data Team • 05/06/2026
The buffer overflow vulnerability identified as CVE-2021-29361 resides within the IrfanView image viewer version 4.57 at the FORMATS!Read_Utah_RLE+0x340 memory location. This critical flaw specifically affects the software's handling of Utah RLE image files, which are commonly used in scientific and medical imaging applications. The vulnerability arises from insufficient bounds checking during the parsing of RLE file headers and data structures, creating an exploitable condition that can be triggered through maliciously crafted input files. The flaw represents a classic buffer overflow scenario where attacker-controlled data exceeds the allocated memory buffer boundaries, potentially allowing for arbitrary code execution with the privileges of the affected application.
This vulnerability operates under the Common Weakness Enumeration category CWE-121, which describes "Stack-based Buffer Overflow" conditions where insufficient validation of input data leads to memory corruption. The attack vector specifically targets the image parsing functionality of IrfanView, making it particularly dangerous in environments where users might encounter untrusted image files from unknown sources. The overflow occurs during the Utah RLE decoding process when the application attempts to read and process compressed image data without proper validation of the data size against the allocated buffer space. This type of vulnerability is classified under the ATT&CK technique T1203, "Exploitation for Client Execution," as it enables remote code execution through compromised image files that are opened by the vulnerable application.
The operational impact of CVE-2021-29361 extends beyond simple arbitrary code execution, as it can be leveraged to escalate privileges and establish persistent access within affected systems. When an attacker successfully exploits this vulnerability, they can execute malicious code within the context of the IrfanView process, potentially leading to full system compromise depending on the user's privileges. The vulnerability affects all systems running IrfanView 4.57 or earlier versions, making it particularly concerning given the widespread adoption of this image viewing application across various industries. The exploitation typically requires the victim to open a specially crafted RLE file, making social engineering and targeted attacks more effective. Organizations relying on IrfanView for document viewing and image processing face significant risk exposure, especially in environments where users may inadvertently open malicious attachments or browse untrusted websites containing compromised image files.
Mitigation strategies for CVE-2021-29361 primarily involve immediate software updates to the latest version of IrfanView, which contains patches addressing the buffer overflow condition. System administrators should implement strict file validation policies and restrict user access to potentially malicious image files through network-level filtering and endpoint protection solutions. The vulnerability can be addressed through proper input validation techniques such as implementing bounds checking and using safe string handling functions that prevent buffer overflows. Organizations should also consider deploying application whitelisting solutions to prevent execution of untrusted image processing applications and implement regular security assessments to identify other potential vulnerabilities in similar image parsing libraries. Additionally, user education regarding safe browsing practices and the dangers of opening unknown image files can significantly reduce the risk of successful exploitation attempts. The fix typically involves modifying the RLE file parsing code to validate input data size before processing and ensuring that memory allocation accounts for all possible data variations within the compressed format specification.