CVE-2026-106110 in ImageSharp
Summary
by MITRE • 10/06/2026
ImageSharp is a 2D graphics library. From 2.0.0 until 4.1.2, the TIFF CCITT Group 3 encoder allocates an undersized compressed-data buffer for narrow 1-bit images. TiffCcittCompressor.Initialize does not reserve enough space for the row data and T4 end-of-line codes, and T4BitCompressor.CompressStrip reaches unchecked writes when TiffCompression.CcittGroup3Fax is selected directly or inherited from decoded TIFF metadata. An attacker-controlled encode or decode-and-re-encode flow can write beyond the logical output span, corrupt process memory, and terminate the process. This issue is fixed in version 4.1.2.
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Analysis
by VulDB Data Team • 10/06/2026
ImageSharp versions ranging from 2.0.0 through 4.1.2 contain a critical buffer overflow vulnerability within its TIFF CCITT Group 3 encoder implementation. The core technical flaw resides in the TiffCcittCompressor.Initialize method, which fails to allocate sufficient memory for compressed data buffers when processing narrow one-bit images. Specifically, the initialization logic does not reserve adequate space to accommodate both the row data and the necessary T4 end-of-line codes required by the CCITT Group 3 compression standard. This miscalculation results in an undersized buffer that cannot safely hold the complete output of the compression operation for specific image dimensions.
The vulnerability is triggered when the T4BitCompressor.CompressStrip method executes under conditions where TiffCompression.CcittGroup3Fax is selected either directly by application code or inherited from decoded TIFF metadata. Because the allocated buffer is smaller than the actual data volume generated during compression, the compressor performs unchecked writes that extend beyond the logical boundaries of the output span. This out-of-bounds write operation allows an attacker to corrupt adjacent memory regions within the process address space. Such corruption can lead to unpredictable application behavior, including crashes and denial of service conditions where the process terminates abruptly due to memory protection violations or stack smashing detection mechanisms triggered by the runtime environment.
From a security classification perspective, this vulnerability aligns with CWE-120 Buffer Copy without Checking Size of Input Classic buffer overflow and potentially CWE-787 Out-of-bounds Write depending on the specific execution context and platform protections in place. In terms of attack vectors, an adversary could exploit this flaw through an attacker-controlled encode or decode-and-re-encode flow to achieve arbitrary code execution if adjacent memory structures are carefully targeted, although the primary observed impact is process termination. This aligns with ATT&CK techniques related to exploitation for denial of service and potentially privilege escalation if the compromised process runs with elevated privileges.
The operational impact of this vulnerability extends beyond simple application crashes. In server-side environments processing user-uploaded images or automated image pipelines, an attacker could send specially crafted narrow one-bit TIFF files designed to trigger the buffer overflow during encoding operations. This would result in service disruption and potential instability that affects downstream services relying on ImageSharp for image manipulation. The lack of bounds checking means that even minor variations in input data can lead to significant memory corruption events that are difficult to debug without specialized forensic analysis tools.
Mitigation strategies primarily involve upgrading the ImageSharp library to version 4.1.2 or later, where this buffer allocation logic has been corrected to properly account for all necessary compression overheads including end-of-line codes. For environments unable to immediately upgrade, implementing strict input validation and size restrictions on TIFF files before they are processed by the encoder can reduce exposure. Additionally, enabling memory protection features such as Address Space Layout Randomization ASLR and Data Execution Prevention DEP at the operating system level can mitigate the risk of arbitrary code execution resulting from this buffer overflow, although these controls do not prevent the initial denial of service condition caused by process termination.