CVE-2026-59198 in Pillow
Summary
by MITRE • 07/14/2026
Pillow is a Python imaging library. From 5.2.0 until 12.3.0, Pillow's TGA RLE encoder reads past its packed row buffer when saving a mode 1 image with TGA RLE compression, allowing adjacent process heap bytes to be copied into the generated TGA file. This issue is fixed in version 12.3.0.
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Analysis
by VulDB Data Team • 07/14/2026
This vulnerability affects the Pillow Python imaging library and represents a classic buffer overread flaw that can lead to information disclosure through heap content leakage. The issue specifically manifests in versions 5.2.0 through 12.3.0 when processing TGA images with RLE compression, particularly impacting mode 1 images that utilize run-length encoding. The vulnerability stems from improper bounds checking within the TGA RLE encoder implementation where the code reads beyond the allocated buffer boundaries during the packing process of image rows.
The technical flaw occurs in the TGA file format handling logic where the encoder attempts to compress image data using run-length encoding without adequate validation of buffer limits. When processing mode 1 images, which typically represent binary data with only black and white pixels, the RLE compression algorithm reads past the intended buffer boundaries into adjacent heap memory regions. This overread operation causes the encoder to copy unintended bytes from process heap memory into the output TGA file, potentially exposing sensitive data that was previously stored in those memory locations.
The operational impact of this vulnerability extends beyond simple information disclosure as it can lead to exposure of arbitrary heap contents including but not limited to cryptographic keys, session tokens, personal data, or other sensitive information that may have resided in the affected memory regions. Attackers could potentially exploit this flaw by creating malicious TGA images that trigger the vulnerable code path, allowing them to harvest heap contents from processes that use Pillow for image processing. This type of vulnerability aligns with CWE-125, which describes out-of-bounds read conditions where a program reads data past the end of a valid buffer.
From an adversarial perspective, this vulnerability can be leveraged in various attack scenarios including memory corruption exploitation or side-channel attacks where attackers analyze leaked heap contents to reconstruct sensitive information. The issue demonstrates poor input validation and boundary checking practices within the image processing pipeline, representing a significant security concern for applications that process untrusted image files through Pillow. Security practitioners should note that this vulnerability is particularly concerning in environments where image processing occurs on user-uploaded content or in server-side applications handling multiple concurrent image operations.
The fix implemented in version 12.3.0 addresses the root cause by introducing proper bounds checking and buffer validation within the TGA RLE encoder. This remediation follows standard secure coding practices that emphasize defensive programming techniques such as input validation, buffer size verification, and memory access boundary checks. Organizations should prioritize upgrading to Pillow version 12.3.0 or later to mitigate this vulnerability, while also implementing additional security measures including image file validation, sandboxed processing environments, and regular security auditing of third-party libraries used in image processing workflows. The vulnerability serves as a reminder of the importance of proper memory management in multimedia processing libraries and aligns with ATT&CK tactic TA0001 (Initial Access) through file upload exploits and TA0002 (Execution) through potential privilege escalation via sensitive data exposure.