SAIL Library - CraftedSignal Threat Feedhttps://feed.craftedsignal.io/products/sail-library/Trending threats, MITRE ATT&CK coverage, and detection metadata. Fed continuously.Hugoenhello@craftedsignal.iohello@craftedsignal.ioWed, 24 Jan 2024 12:00:00 +0000SAIL Library XWD Codec Out-of-Bounds Read Vulnerability (CVE-2026-40492)https://feed.craftedsignal.io/briefs/2024-01-24-sail-xwd-codec-oob-read/Wed, 24 Jan 2024 12:00:00 +0000hello@craftedsignal.iohttps://feed.craftedsignal.io/briefs/2024-01-24-sail-xwd-codec-oob-read/A memory access vulnerability exists in the SAIL image library's XWD codec due to inconsistent handling of pixel format, potentially leading to crashes or code execution when processing specially crafted image files.The SAIL (Simple API for Images Loading) library, a cross-platform tool used for loading and saving images, contains a critical vulnerability (CVE-2026-40492) within its XWD codec. This flaw stems from inconsistent handling of pixel format (pixmap_depth) and bit depth (bits_per_pixel) during image processing. Specifically, the byte-swap code within the XWD codec incorrectly accesses memory when pixmap_depth is set to 8 (indicating 1 byte per pixel) while bits_per_pixel is set to 32. This discrepancy causes the code to read and write 4x the allocated buffer size, resulting in an out-of-bounds memory access. This is a distinct vulnerability from CVE-2026-27168. The vulnerability was patched in commit 36aa5c7ec8a2bb35f6fb867a1177a6f141156b02. Successful exploitation could lead to application crashes, denial-of-service, or potentially arbitrary code execution.

Attack Chain

  1. An attacker crafts a malicious XWD image file with pixmap_depth set to 8 and bits_per_pixel set to 32.
  2. A user or application unknowingly processes the malicious XWD image file using the vulnerable SAIL library.
  3. The SAIL library's XWD codec attempts to decode the image.
  4. During the byte-swapping process, the codec incorrectly calculates the memory access size based on bits_per_pixel (32) while using a buffer size based on pixmap_depth (8).
  5. The byte-swap loop attempts to read and write 4 bytes per pixel, exceeding the allocated buffer size.
  6. This results in an out-of-bounds read and write operation, potentially overwriting adjacent memory regions.
  7. If the overwritten memory contains critical data or executable code, it could lead to application instability or code execution.
  8. The attacker achieves denial of service or potentially gains control of the affected system.

Impact

Successful exploitation of CVE-2026-40492 can have severe consequences. An attacker could cause applications using the SAIL library to crash, leading to denial of service. In more severe scenarios, the out-of-bounds write could be leveraged to execute arbitrary code, potentially allowing the attacker to gain control of the affected system. The number of potential victims is broad, as the SAIL library is used across multiple platforms and applications that process image files. Sectors that rely heavily on image processing, such as graphic design, medical imaging, and digital photography, are particularly at risk.

Recommendation

  • Upgrade the SAIL library to a version containing commit 36aa5c7ec8a2bb35f6fb867a1177a6f141156b02 or later to patch CVE-2026-40492.
  • Monitor applications that use the SAIL library for unexpected crashes or memory access violations (requires robust application logging).
  • Consider implementing input validation on image files to ensure that pixmap_depth and bits_per_pixel values are consistent and within expected ranges, though this is not a complete defense and requires careful implementation.
]]>criticaladvisorycve-2026-40492sailxwdimage-processingmemory-corruptionSAIL Library TGA RLE Decoder Heap Overflow Vulnerabilityhttps://feed.craftedsignal.io/briefs/2024-01-sail-tga-rle-heap-overflow/Wed, 03 Jan 2024 12:00:00 +0000hello@craftedsignal.iohttps://feed.craftedsignal.io/briefs/2024-01-sail-tga-rle-heap-overflow/The SAIL library versions before commit 45d48d1f2e8e0d73e80bc1fd5310cb57f4547302 are vulnerable to a heap overflow in the TGA codec's RLE decoder, where the raw-packet path lacks bounds checking, potentially leading to privilege escalation via crafted image files.The SAIL library, a cross-platform solution for image loading and saving, is susceptible to a critical vulnerability (CVE-2026-40494) affecting versions prior to commit 45d48d1f2e8e0d73e80bc1fd5310cb57f4547302. The vulnerability resides within the Truevision Graphics Adapter (TGA) codec's Run-Length Encoding (RLE) decoder specifically in tga.c. The flaw stems from an asymmetric bounds check in the RLE decoder. While the run-packet path includes necessary bounds checking, the raw-packet path lacks this safeguard. This omission allows a malicious actor to craft a TGA image that, when processed by a vulnerable application, triggers a heap overflow by writing up to 496 bytes beyond the allocated buffer. This vulnerability poses a significant risk as it can be exploited to achieve arbitrary code execution and privilege escalation on systems utilizing the affected SAIL library. The scope of targeting includes any application utilizing the vulnerable SAIL library on Windows, Linux, or macOS.

Attack Chain

  1. An attacker crafts a malicious TGA image file exploiting the missing bounds check in the RLE decoder's raw-packet path.
  2. The attacker delivers the malicious TGA image to a target system, potentially via a website upload, email attachment, or other file transfer mechanisms.
  3. A vulnerable application using the SAIL library attempts to load the malicious TGA image.
  4. The TGA codec's RLE decoder processes the image data within tga.c.
  5. Due to the absence of bounds checking in the raw-packet path (lines 305-311), the decoder writes attacker-controlled data beyond the allocated heap buffer.
  6. The heap overflow corrupts adjacent memory regions, potentially overwriting critical data structures or function pointers.
  7. The corrupted memory leads to a crash or, more critically, allows the attacker to hijack program execution.
  8. Successful exploitation enables the attacker to execute arbitrary code with the privileges of the vulnerable application, leading to privilege escalation.

Impact

Successful exploitation of CVE-2026-40494 allows an attacker to achieve arbitrary code execution with the privileges of the application using the vulnerable SAIL library. The impact is severe, as it can lead to complete system compromise, data exfiltration, or denial of service. The number of potential victims is broad, including any user or organization employing applications that rely on the affected SAIL library for image processing across various sectors. While specific victim numbers remain unknown, the cross-platform nature of the library suggests widespread potential impact.

Recommendation

  • Upgrade the SAIL library to a version containing the fix for CVE-2026-40494, specifically commit 45d48d1f2e8e0d73e80bc1fd5310cb57f4547302.
  • Deploy the Sigma rules provided in this brief to your SIEM to detect potential exploitation attempts.
  • Implement input validation and sanitization measures to restrict the types and sizes of image files processed by applications using the SAIL library.
  • Monitor applications using the SAIL library for unexpected crashes or abnormal behavior, which could indicate exploitation attempts.
  • Enable process creation logging with command line arguments to allow detection of suspicious processes spawned by applications processing images.
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