Double Free vulnerability in Nothings Stb Image.h v.2.28 allows a remote attacker to cause a denial of service via a crafted file to the stbi_load_gif_main function.

stb_image is a single file MIT licensed library for processing images. If `stbi__load_gif_main` in `stbi_load_gif_from_memory` fails it returns a null pointer and may keep the `z` variable uninitialized. In case the caller also sets the flip vertically flag, it continues and calls `stbi__vertical_flip_slices` with the null pointer result value and the uninitialized `z` value. This may result in a program crash.

stb_image is a single file MIT licensed library for processing images. It may look like `stbi__load_gif_main` doesn’t give guarantees about the content of output value `*delays` upon failure. Although it sets `*delays` to zero at the beginning, it doesn’t do it in case the image is not recognized as GIF and a call to `stbi__load_gif_main_outofmem` only frees possibly allocated memory in `*delays` without resetting it to zero. Thus it would be fair to say the caller of `stbi__load_gif_main` is responsible to free the allocated memory in `*delays` only if `stbi__load_gif_main` returns a non null value. However at the same time the function may return null value, but fail to free the memory in `*delays` if internally `stbi__convert_format` is called and fails. Thus the issue may lead to a memory leak if the caller chooses to free `delays` only when `stbi__load_gif_main` didn’t fail or to a double-free if the `delays` is always freed

stb_image is a single file MIT licensed library for processing images. A crafted image file can trigger `stbi__load_gif_main_outofmem` attempt to double-free the out variable. This happens in `stbi__load_gif_main` because when the `layers * stride` value is zero the behavior is implementation defined, but common that realloc frees the old memory and returns null pointer. Since it attempts to double-free the memory a few lines below the first “free”, the issue can be potentially exploited only in a multi-threaded environment. In the worst case this may lead to code execution.

stb_image is a single file MIT licensed library for processing images. The stbi__getn function reads a specified number of bytes from context (typically a file) into the specified buffer. In case the file stream points to the end, it returns zero. There are two places where its return value is not checked: In the `stbi__hdr_load` function and in the `stbi__tga_load` function. The latter of the two is likely more exploitable as an attacker may also control the size of an uninitialized buffer.

stb_image is a single file MIT licensed library for processing images. When `stbi_set_flip_vertically_on_load` is set to `TRUE` and `req_comp` is set to a number that doesn’t match the real number of components per pixel, the library attempts to flip the image vertically. A crafted image file can trigger `memcpy` out-of-bounds read because `bytes_per_pixel` used to calculate `bytes_per_row` doesn’t match the real image array dimensions.

stb_image is a single file MIT licensed library for processing images. A crafted image file may trigger out of bounds memcpy read in `stbi__gif_load_next`. This happens because two_back points to a memory address lower than the start of the buffer out. This issue may be used to leak internal memory allocation information.

Nothings stb 2.28 was discovered to contain a Null Pointer Dereference via the function stbi__convert_format. This vulnerability allows attackers to cause a Denial of Service (DoS) via a crafted pic file.