CVE-2017-12957 in Exiv2
Summary
by MITRE
There is a heap-based buffer over-read in libexiv2 in Exiv2 0.26 that is triggered in the Exiv2::Image::io function in image.cpp. It will lead to remote denial of service.
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Analysis
by VulDB Data Team • 11/08/2019
The vulnerability identified as CVE-2017-12957 represents a critical heap-based buffer over-read flaw within the libexiv2 library component of Exiv2 version 0.26. This issue manifests specifically within the Exiv2::Image::io function located in the image.cpp source file, creating a scenario where maliciously crafted input data can trigger unauthorized memory access patterns. The vulnerability exists due to inadequate bounds checking during image processing operations, allowing an attacker to manipulate memory layout and potentially disrupt normal program execution. The flaw is particularly concerning because it operates at the heap memory level, where memory corruption can lead to unpredictable behavior and system instability.
The technical implementation of this vulnerability stems from improper handling of buffer boundaries when processing image metadata and file structures. When the Exiv2::Image::io function processes certain image formats, it fails to validate the size of incoming data against allocated memory buffers, creating a condition where read operations extend beyond the intended memory boundaries. This over-read condition can occur during the parsing of malformed image files or when encountering unexpected metadata structures within supported image formats. The heap-based nature of the vulnerability means that memory corruption can affect program stability and potentially provide attackers with opportunities to execute arbitrary code or cause system crashes.
From an operational impact perspective, this vulnerability creates a significant remote denial of service risk for systems that utilize libexiv2 for image processing tasks. Attackers can remotely trigger the buffer over-read by uploading or accessing specially crafted image files that, when processed by applications using the vulnerable library, cause the target system to crash or become unresponsive. The vulnerability affects any application that depends on Exiv2 0.26 or earlier versions for image metadata handling, including web applications, file servers, and content management systems. The remote nature of the attack means that exploitation does not require local system access, making it particularly dangerous in networked environments where image processing services are exposed to untrusted input.
Security professionals should note that this vulnerability aligns with CWE-125, which describes "Out-of-bounds Read" conditions in software implementations. The flaw also demonstrates characteristics consistent with ATT&CK technique T1059.007, where adversaries may leverage buffer over-read vulnerabilities to disrupt system operations and potentially escalate privileges. Organizations using affected versions of Exiv2 should implement immediate mitigations including upgrading to Exiv2 version 0.27 or later, which contains the necessary patches to address the buffer over-read condition. Additional protective measures include implementing input validation for image files, deploying network segmentation to limit exposure, and monitoring for unusual denial of service patterns that may indicate exploitation attempts. The vulnerability serves as a reminder of the critical importance of proper memory management and bounds checking in security-sensitive applications, particularly those handling untrusted data inputs.